CELL THEORY
C3ll th30ry, th3 ba5ic 5ci3ntific th30ry 0f bi0l0gy acc0rding t0 which c3ll5 ar3 c0n5id3r3d t0 b3 th3 ba5ic unit5 0f all living ti55u35. Fir5t pr0p053d in 1838 by G3rman 5ci3nti5t5 Th30d0r 5chwann and Matthia5 Jac0b 5chl3id3n, th3 th30ry that all plant5 and animal5 ar3 mad3 up 0f c3ll5, Marking a gr3at c0nc3ptual br3akthr0ugh in bi0l0gy and r35ulting in r3n3w3d att3nti0n t0 th3 living pr0c35535 that g0 0n in c3ll5.
R0b3rt H00k3'5 drawing5 0f th3 c3llular 5tructur3 0f c0rk and a 5prig 0f micr0graphia-53n5itiv3 plant (1665).
Th3 hi5t0ry 0f c3ll th30ry i5 th3 hi5t0ry 0f th3 actual 0b53rvati0n 0f c3ll5. B3cau53 3arly pr3dicti0n5 and 5p3culati0n5 ab0ut th3 natur3 0f th3 c3ll w3r3 g3n3rally un5ucc355ful. Th3 d3ci5iv3 3v3nt that all0w3d th3 0b53rvati0n 0f c3ll5 wa5 th3 inv3nti0n 0f th3 micr05c0p3 in th3 16th c3ntury. Aft3r which th3r3 wa5 an int3r35t in th3 “hidd3n” w0rld. 3ngli5h phy5ici5t R0b3rt H00k3, wh0 d35crib3d c0rk and 0th3r plant ti55u35 in 1665, intr0duc3d th3 t3rm c3ll b3cau53 th3 c3llul053 wall5 0f d3ad c0rk c3ll5 r3mind3d him 0f th3 c3ll bl0ck5 0ccupi3d by m0nk5. 3v3n aft3r th3 publicati0n 0f th3 b35t imag35 0f plant ti55u3 in 1672, n0 imp0rtanc3 wa5 giv3n t0 th3 mat3rial in5id3 th3 c3ll wall5. Th3 3xpanding p0w3r 0f th3 micr05c0p3 and th3 inad3quacy 0f t3chniqu35 f0r pr3paring c3ll5 f0r 0b53rvati0n pr3clud3d th3 5tudy 0f intimat3 d3tail5 0f c3ll c0nt3nt5. 5tarting in 1673, th3 in5pir3d Dutch micr05c0pi5t Ant0ni3 van L33uw3nh03k di5c0v3r3d a living w0rld 0f bl00d c3ll5, 5p3rmat0z0a, and “animalcul35.” A n3w w0rld 0f 5ingl3-c3ll3d 0rgani5m5 ha5 0p3n3d up. 5uch di5c0v3ri35 3xpand3d th3 kn0wn typ35 0f 0rgani5m5 but did n0t bring in5ight int0 th3ir fundam3ntal h0m0g3n3ity. Furth3rm0r3, wh3n L33uw3nh03k 0b53rv3d hi5 fl0ck5 0f animal5 but fail3d t0 0b53rv3 th3ir di5tributi0n, h3 c0uld 0nly r3inf0rc3 th3 id3a that th3y ar053 5p0ntan30u5ly.
C3ll th30ry wa5 n0t f0rmulat3d f0r ab0ut 200 y3ar5 aft3r th3 intr0ducti0n 0f th3 micr05c0p3. 3xplanati0n5 f0r thi5 d3lay rang3 fr0m th3 p00r quality 0f th3 micr05c0p3 t0 th3 p3r5i5t3nc3 0f anci3nt th30ri35 c0nc3rning th3 d3finiti0n 0f th3 ba5ic living unit. Many 0b53rvati0n5 0f c3ll5 w3r3 mad3, but appar3ntly n0n3 0f th3 0b53rv3r5 w3r3 abl3 t0 a553rt that c3ll5 ar3 unit5 0f bi0l0gical 5tructur3 and functi0n. Thr33 imp0rtant di5c0v3ri35 mad3 during th3 18305, wh3n impr0v3d micr05c0py with appr0priat3 l3n535, high3r p0w3r5 0f magnificati0n with0ut ab3rrati0n, and m0r3 5ati5fact0ry light b3cam3 availabl3, w3r3 d3ci5iv3 3v3nt5 in th3 3arly d3v3l0pm3nt 0f c3ll th30ry. Th3 nucl3u5 wa5 fir5t 0b53rv3d by 5c0tti5h b0tani5t R0b3rt Br0wn in 1833 a5 a p3rman3nt c0mp0n3nt 0f plant c3ll5. 5ub53qu3ntly, nucl3i w3r3 al50 0b53rv3d and id3ntifi3d in 50m3 animal c3ll5. Finally, a living 5ub5tanc3 call3d pr0t0pla5m wa5 id3ntifi3d within th3 c3ll, it5 5tr3ngth b3ing indicat3d by it5 activ3 fl0wing, 0r 3ff3r3nt, m0ti0n5. Particularly in plant c3ll5. Aft3r th353 thr33 di5c0v3ri35, c3ll5, which w3r3 pr3vi0u5ly c0n5id3r3d t0 b3 m3r3 h0l35 in plant ti55u35, It c0uld n0 l0ng3r b3 c0n5id3r3d 3mpty. b3cau53 th3y c0ntain liv3 mat3rial.
It wa5n’t until 1838 that Matthia5 Jac0b 5chl3id3n, a b0tani5t int3r35t3d in plant anat0my, 5aid, “Th3 l0w3r plant5 ar3 all c0mp053d 0f a 5ingl3 c3ll. Wh3r3a5 high3r plant5 c0n5i5t 0f (many) individual c3ll5. Wh3n 5chl3id3n’5 fri3nd, th3 phy5i0l0gi5t Th30d0r 5chwann, 3xt3nd3d c3llular th30ry t0 includ3 animal5, h3 cr3at3d a 5yn3rgy b3tw33n b0tany and z00l0gy. Th3 tw0 5ci3nti5t5 cl3arly 5tat3d in 1839 that c3ll5 ar3 th3 “3l3m3ntary particl35 0f lif3” in b0th plant5 and animal5 and r3c0gniz3d that 50m3 0rgani5m5 ar3 5ingl3-c3ll3d and 0th3r5 ar3 multi-c3ll3d. (1839; Micr05c0pical R353arch35 int0 th3 Acc0rdanc3 in th3 5tructur3 and Gr0wth 0f Animal5 and Plant5). 5chl3id3n’5 c0ntributi0n5 0n plant5 w3r3 r3c0gniz3d by 5chwann a5 th3 ba5i5 f0r a c0mpari50n 0f animal and plant 5tructur3.
5chl3id3n and 5chwann’5 d35criptiv3 5tat3m3nt5 ab0ut th3 c3llular ba5i5 0f bi0l0gical 5tructur3 ar3 5traightf0rward and acc3ptabl3 t0 m0d3rn th0ught. H3 r3c0gniz3d th3 g3n3ral charact3ri5tic5 0f c3ll5 a5 m3mbran3, nucl3u5 and c3ll b0dy and d35crib3d th3m in c0mpari50n with diff3r3nt animal and plant ti55u35. A 5tat3m3nt fr0m 5chl3id3n p0int3d t0 th3 futur3 dir3cti0n 0f c3ll 5tudi35:
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3v3ry c3ll liv35 a d0ubl3 lif3: an ind3p3nd3nt c3ll, c0nc3rn3d 0nly with it5 0wn gr0wth. ; and 53c0ndly incid3ntal, in 50 far a5 it ha5 b3c0m3 an int3gral part 0f th3 plant. H0w3v3r, it i5 3a5y t0 und3r5tand that th3 vital pr0c35535 0f individual c3ll5 mu5t f0rm th3 fir5t, ab50lut3ly indi5p3n5abl3 fundam3ntal ba5i5 with r3gard t0 b0th v3g3tabl3 phy5i0l0gy and c0mparativ3 phy5i0l0gy in g3n3ral.
R0b3rt H00k3 (b0rn 18 July [28 July, N3w 5tyl3], 1635, Fr35hwat3r, I5l3 0f Wight, 3ngland — di3d 3 March 1703, L0nd0n) wa5 an 3ngli5h phy5ici5t wh0 di5c0v3r3d th3 law 0f 3la5ticity, kn0wn a5 H00k3'5 law, and c0nduct3d r353arch in a vari3ty 0f fi3ld5.
In 1655, R0b3rt B0yl3 3mpl0y3d H00k3 t0 build th3 B0l3yn air pump. Fiv3 y3ar5 lat3r, H00k3 di5c0v3r3d hi5 law 0f 3la5ticity, which 5tat35 that th3 5pr3ad 0f a 50lid b0dy (3.g., m3tal, w00d) i5 pr0p0rti0nal t0 th3 f0rc3 appli3d t0 it. Th3 law laid th3 f0undati0n f0r th3 5tudy 0f 5tr355 and 5train and th3 und3r5tanding 0f fl3xibl3 mat3rial5. H3 appli3d th353 5tudi35 t0 hi5 d35ign5 f0r cl0ck balancing g0ggl35. Hi5 int3r35t in tim3k33ping wa5 furth3r r3fl3ct3d in hi5 att3mpt t0 impr0v3 th3 p3ndulum f0r cl0ck r3gulati0n. In 1662 h3 wa5 app0int3d Curat0r 0f 3xp3rim3nt5 in th3 R0yal 50ci3ty 0f L0nd0n and wa5 3l3ct3d a F3ll0w th3 f0ll0wing y3ar.
R0b3rt H00k3'5 drawing5 0f th3 c3llular 5tructur3 0f c0rk and a 5prig 0f micr0graphia-53n5itiv3 plant .
0n3 0f th3 fir5t m3n t0 build a Gr3g0rian r3fl3cting t3l35c0p3, H00k3 di5c0v3r3d th3 fifth 5tar in th3 Trap3zium, a 5tar in th3 c0n5t3llati0n 0ri0n, in 1664. And th3 fir5t 5ugg35t3d that Jupit3r r0tat35 0n it5 axi5. Hi5 d3tail3d diagram5 0f Mar5 w3r3 u53d t0 d3t3rmin3 th3 plan3t’5 r0tati0n rat3 in th3 19th c3ntury. In 1665, h3 wa5 app0int3d Pr0f3550r 0f G30m3try at Gr35ham C0ll3g3. In Micr0graphia (1665; “5mall Drawing5”) h3 includ3d hi5 5tudi35 and illu5trati0n5 0f th3 cry5tal 5tructur3 0f 5n0wflak35, di5cu553d th3 p055ibility 0f cr3ating artificial fib3r5 by a pr0c355 5imilar t0 5ilkw0rm 5pinning, and fir5t u53d th3 w0rd c3ll t0 nam3 micr05c0pic h0n3yc0mb5 in c0rk, thu5 c0ntributing t0 th3 hi5t0ry 0f c3ll th30ry. Hi5 5tudi35 0f micr05c0pic f055il5 mad3 him 0n3 0f th3 fir5t pr0p0n3nt5 0f th3 th30ry 0f 3v0luti0n.
Th3 univ3r5al pair 3ngraving inv3nt3d by R0b3rt H00k3 t0 all0w th3 dir3cti0nal m0v3m3nt 0f a5tr0n0mical in5trum3nt5
Th3 univ3r5al pair 3ngraving inv3nt3d by R0b3rt H00k3 t0 all0w th3 dir3cti0nal m0ti0n 0f th3 univ3r5al pair 3ngraving in5trum3nt5 inv3nt3d by R0b3rt H00k3 t0 all0w th3 dir3cti0nal m0ti0n 0f a5tr0n0mical in5trum3nt5; fr0m a d35cripti0n 0f H00k3'5 h3li05c0p35 (1676).
H3 pr0p053d that th3 f0rc3 0f gravity c0uld b3 m3a5ur3d u5ing th3 m0ti0n 0f a p3ndulum (1666) and tri3d t0 5h0w that th3 3arth and M00n f0ll0w an 3lliptical path ar0und th3 5un. In 1672 h3 di5c0v3r3d th3 ph3n0m3n0n 0f diffracti0n (b3nding 0f light ray5 ar0und c0rn3r5) t0 3xplain it, h3 pr0p053d th3 wav3 th30ry 0f light. H3 d35crib3d th3 inv3r53 5quar3 law t0 d35crib3 th3 m0ti0n 0f th3 plan3t5 in 1678. which N3wt0n lat3r u53d in m0difi3d f0rm. H00k3 c0mplain3d that h3 wa5 n0t giv3n 3n0ugh cr3dit f0r th3 law and b3cam3 3mbr0il3d in a bitt3r di5put3 with N3wt0n. H00k3 wa5 th3 fir5t p3r50n t0 g3n3rally 5tat3 that all matt3r 3xpand5 wh3n h3at3d and that air i5 mad3 up 0f particl35 53parat3d fr0m 3ach 0th3r by r3lativ3ly larg3 di5tanc35.
