NATURE 



193 



THURSDAY, JULY 



1896. 



THE CELL-THEORY. 

 Lemons sur /a Cellule Morp/iologie el Re'production fuites 

 au College de France pendant le semestre d'hiver 

 1893-94. Par F(51ix Henneguy. Pp. xix + 541. 362 

 figures. (Paris: Georges Carre, 1896.) 



THE cell occupies, and has for half a century occu- 

 pied, so important a position in biological science, 

 that the literature dealing with it and the number of general 

 works called up by this literature has become enormous, 

 and is daily increasing. Nor is this a matter to be 

 wondered at, for the subject is one of supreme import- 

 ance to the biologist, and contains within its border the 

 very innermost mysteries of life. But in saying this, we 

 do not wish to be understood as giving our adhesion 

 to this or to that modern school of thought with regard 

 to the importance of the cell in organisms. It is suffi- 

 cient for us to note the fact that, great as has been the 

 influence of the conception of cell on biological investi- 

 gations in the last fifty years, the chief merit of the 

 founders of the cell-theory lay less in giving us that 

 conception than in fixing attention upon the matter of 

 which the organism is composed. To the cell-theory 

 we owe our conception of the organism as a body coni- 

 posed of protoplasm — the real living matter, and of 

 formed material — the non-living or semi-living frame- 

 work. The former is the true seat of life, and the latter 

 is produced as a result of its vital activity. This con- 

 ception has been an analytical tool of the most powerful 

 kind, and has assisted very considerably in the task of 

 unraxelling the complexity of structure and function of 

 tlie parts of organisms. The cell-theory first fixed our 

 attention upon protoplasm, and upon that most important 

 part of protoplasm the nucleus ; and it is to the study 

 of protoplasm and of the nucleus, of their structure, 

 relations, and activities, that the great advances in modern 

 biolojiy are due. This, we repeat, was the great work 

 of the founders of the cell-theory. But they did more 

 than this : they first showed us that the living substance 

 is often arranged in and works through small structural 

 units called cells ; and they first gave us the idea that 

 the organism is composed of independent or semi-inde- 

 pendent individuals associated together in a colony for 

 the common good. It is this idea, this hypothetical ex- 

 planation of cellular structure, which constitutes the 

 cell-theory ; and it must be clearly borne in mind that 

 the promulgation of this hypothesis was the least im- 

 portant part of the work of the founders of that theory. 

 At the same time it is an undeniable fact that this 

 hypothesis was held, and indeed is held largely at the 

 present day ; and that it has had a most important 

 influence upon biological research. Of its value we 

 express no opinion, but we should be wanting in our 

 duty if we did not point out that of late years a slowly 

 increasing number of biologists have cast doubts upon 

 its validity and utility as an explanation of cellular 

 structure, and are content to hold for the present that 

 cellular structure has not received any adequate explan- 

 ation, or, to use the somewhat vague words of Sachs, is 

 a phenomenon of secondary significance, and merely 

 NO. 1392. VOL. 54] 



one of the numerous expressions of the formative forces 

 which reside in all matter, and in the highest degree in 

 organic substance. 



It is obvious that a work dealing with the cell 

 in this wide sense, viz. as an equivalent for proto- 

 plasm- and nucleus, must have a very large scope 

 indeed ; for if complete, it would include the whole of 

 vegetable and animal histology and physiology. Owing 

 to human limitations, it is in these days impossible 

 for a single author to take this wide outlook, and we 

 find in works dealing with the cell restrictions of various 

 kinds. As a general rule, an author will limit himself 

 to animal or to vegetable protoplasm, and a full con- 

 sideration of the formed material is nearly always 

 excluded. The part of the subject to which special 

 attention is devoted — at any rate in recent works — is 

 the structure of protoplasm, and of the nucleus and the 

 behaviour of the nucleus in division and in conjugation. 

 M. Henneguy is not content with any restriction of this 

 kind, and though modestly disclaiming all idea of giving 

 a complete account of the subject, and of having written 

 a treatise on Cytology, he has in our opinion produced a 

 more complete work on protoplasm and the nucleus than 

 any of his predecessors. The work represents a course 

 of thirty-one lectures given at the College de France in 

 the winter of 1893-4, and is an admirable account of the 

 state of our knowledge to that date. The author deals 

 both with animal and vegetable protoplasm, with its 

 chemical and physical constitution, with its structure, 

 with the nucleus, the change which it undergoes and its 

 relation to the cytoplasm, and with its division and 

 its conjugation. An account of the nutrition of the 

 cell, of the products of cellular activity, and of its func- 

 tional differentiation, occupies a prominent place in the 

 work. Fmally he has a chapter on the relation ot 

 cells to each other, and another on the most important 

 hypotheses on the constitution of protoplasm, and he 

 begins the work by an excellent account of the growth 

 of knowledge on the subject. 



The work is of course a didactic one, and in no sense 

 is to be regarded as an original contribution to know- 

 ledge. The author's object is to give an account of the 

 facts which have been definitely established, relegating 

 to the second place controversial or doubtful matters. 



And in this he does well, for, as he points out, the 

 tendency at the present day among a certain class of 

 small workers to premature publication and to hasty 

 generalisation, leads to most disastrous results in the 

 accumulation of third-rate literature. A single fact, which 

 often turns out to be no fact at all, is hidden in pages of 

 raw and worthless speculation. " Another cause assists 

 in accentuating this pernicious tendency. In certain 

 schools far too much emphasis is laid upon new and still 

 controverted observations, and classical works confirmed 

 by numerous and reiterated observations are too often 

 neglected, and future observers thus deprived of a sure 

 and solid basis." He devotes a special section to the 

 consideration of the effects of the different kinds of 

 reagents used by histologists in altering the structure of 

 protoplasm, and he calls the attention of his readers to 

 the importance of the study of living protoplasm, and of 

 checking all their results by it. This is a most important 

 point, too often lost sight of in the rush and petty 



K 



