CELL AND PROTOPLASM CONCEPTS 



mals. The most notable of these was Cas- 

 par Frederich Wolff (1733-1794). His 

 thesis for the M.D. degree, published in 

 1759 when he was only 26 years old, was 

 entitled Theoria Generationis and it marks 

 an epoch in the study of the development 

 of plants and animals. Wolff showed that 

 in their development animals and plants 

 are composed of "globules or utricles 

 which may always be distinguished under 

 a microscope of moderate magnification." 

 He supposed that utricles arise as vacuoles 

 in a homogeneous jelly. According to von 

 Sachs, his was the most important work of 

 the period between Grew, 1672, and Mirbel, 

 1808. "It was Wolff's doctrine of the for- 

 mation of cellular structures in plants 

 which was adopted in the main, by Mirbel ' ' 

 (v. Sachs, History of Botany). 



For more than one hundred years the 

 words "utricles," "vesicles" or "glob- 

 ules" were used to designate these con- 

 stituent parts of animals and plants, and 

 only in the beginning of the 19th century 

 did Hooke's term "cell" again come into 

 use. In 1808 and 1809, Brisseau de Mirbel 

 (1776-1854), professor of botany in the 

 Musee d 'Historic Naturelle in Paris, pub- 

 lished a notable work on his theory of 

 plant organization ("Theorie de 1 'organi- 

 zation vegetale"). The general conclu- 

 sions of this work were that "the plant is 

 wholly formed of a continuous cellular 

 membranous tissue." In a set of "Apho- 

 risms" that he had prepared to accompany 

 a large plate illustrating the finer structure 

 of plants he wrote, "Plants are made up of 

 cells, all parts of which are in continuity 

 and form one and the same membranous 

 tissue." It is apparent from this that 

 while Mirbel recognized the universal pres- 

 ence of cells in plants, he also regarded 

 them as bound together in a membranous 

 tissue. 



Professor John H. Gerould (1922), in an 

 important paper entitled "The Dawn of 

 the Cell Theory," has shown that the great 

 French naturalist, Lamarck (1744-1829), 

 deserves to rank as one of the founders of 

 the cell theory. In his Philosophie ZooU 

 ogique published in 1809 he says: "No 

 body can possess life if its containing parts 



are not a cellular tissue, or formed by 

 cellular tissue." Again: 



Thus every living body is essentially a mass of 

 cellular tissue in which more or less complex fluids 

 move more or less rapidly; so that if this body is 

 very simple, that is without special organs, it ap- 

 pears homogeneous and presents nothing but cellu- 

 lar tissue containing fluids which move within it 

 slowly; but if its organization is complex all its 

 organs without exception, as well as their most 

 minute parts, are enveloped in cellular tissue, and 

 even are essentially formed of it. 



In the second volume of his great work 

 Lamarck devotes an entire chapter to cellu- 

 lar tissues, in which he says: y 



It has been recognized for a long time that the 

 membranes that form the envelopes of the brain, 

 of nerves, of vessels of all kinds, of glands, of 

 viscera, of muscles and their fibers, and even the 

 skin of the body are in general the productions of 

 cellular tissue. However, it does not appear that 

 anyone has seen in this multitude of harmonizing 

 facts anything but the facts themselves; and no 

 one, so far as I know, has yet perceived that cellu- 

 lar tissue is the general matrix of all organization, 

 and that without this tissue no living body would 

 be able to exist nor could have been formed. Since 

 the year 1796 I have been accustomed to set forth 

 these principles in the first lessons of my course. 



Everywhere Lamarck speaks of cellular 

 tissue and apparently neither he nor Mir- 

 bel thought of the cell as an independent 

 unit. This idea was more clearly expressed 

 in 1824 by Dutrochet, a French physiolo- 

 gist and physicist, in the following words: 



All the organic tissues of animals are actually 

 globular cells of exceeding smallness, which appear 

 to be united only by a simple adhesive force; thus 

 all tissues, all animal organs, are actually only a 

 cellular tissue variously modified. This uniformity 

 of finer structure proves that organs actually differ 

 among themselves merely in the nature of the sub- 

 stances contained in the vesicular cells, of which 

 they are entirely composed. 



Another French naturalist who seems to 

 have escaped recent notice was J. P. F. 

 Turpin (1775-1840), who published in 

 1826 a remarkable memoir with a title so 

 complete that it forms an abstract of the 

 contents : 



Organographie microscopique elemeutaire et com- 

 paree des vegetaux. Observations sur I'origine et 

 la formation primitive du tissue cellulaire, sur 

 chacune des vesicules composantes de ce tissu, con- 

 siderees comme autant d 'individualites distinctes 

 ayant leur centre vital particulier de vegetation et 



