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SCIENCE 



[N. S. Vol. XXXIV. No. 867 



or indirect, wliicli they are making toward 

 state endowments for medical education in 

 Nebraska, Illinois and elsewhere. This oppo- 

 sition, however, will not be misunderstood 

 and the progress for better standards of med- 

 ical education has received too much impetus 

 to be stopped by obstructions prompted by 

 selfish interests. It is not only the right, but 

 also the duty, of each state to provide a 

 good training for those who are to have in 

 charge the health of the people of that com- 

 monwealth as is the case in nearly all other 

 countries. — Journal of the American Medical 

 Association. 



SCIENTIFIC BOOKS 

 Some Neglected Factors in Evolution. An 



Essay in Constructive Biology. By Henry 



M. Bernard, edited by Matilda Bernard. 



ISTew York and London, G. P. Putnam's 



Sons. 1911. 



The late Mr. H. M. Bernard has written 

 several works which testify to a painstaking 

 industry and a desire to take a broad view of 

 the problems which arose in connection with 

 his line of work. His more important con- 

 tributions to zoology were volumes on the 

 Apodidse, the " Catalogue of the Madrepora- 

 rian Corals in the British Museum " and his 

 studies on the retina, and it was these last, 

 especially, that were responsible for the ideas 

 expressed in the volume under review, which 

 has been edited from unpublished manuscripts 

 by Mrs. Bernard. Bernard's studies of the 

 retina led him to regard it as a syncytial 

 network, and this conception rendered him 

 skeptical as to the cell as the ultimate struc- 

 tural unit; it seemed to him to demand the 

 postulation of a simpler unit, which might 

 stand in the same relation to the cell as this 

 does to a metazoan. This unit he termed a 

 chromidium and described it as a particle of 

 chromatin from which delicate linin fila- 

 ments radiate, the stellate linin-chromatin 

 mass being " embedded in a minute drop of 

 some fluid albuminous matrix to the surface 

 of which the filaments extend." By the 

 growth and frequent partial division of such 

 a unit a cell is formed, a unit of a higher 



grade and capable of being regarded as a 

 synchromidium in which the chromatin ma- 

 terial has become aggregated mainly at the 

 center of the mass, the linin-filaments of the 

 various component chromidia uniting to form 

 a network and felting together to form the 

 nuclear membrane. By this conception of the 

 cell the author imagined that he had suc- 

 ceeded in reconciling two very divergent 

 theories of cell structure, the chromatin 

 particles being identical with Altmann's 

 granules, while the linin-network produces the 

 appearance which Biitschli had attributed to 

 a foam structure. Just as the chromidium by 

 imperfect division gives rise to the cell per- 

 son represented by the protozoa, so this gives 

 rise to individuals of a higher grade, the gas- 

 traeal unit, represented by the ccslentera and 

 the platyhelminths, and this to an annelidan 

 unit, represented by the remaining groups of 

 animals with the exception of man, who con- 

 stitutes the final grade. And throughout each 

 of these units there is continuity of structure, 

 the linin-filaments forming a continuum 

 throughout the entire organism to whatever 

 grade it may belong, and the chromatin aggre- 

 gating at the nodes of the linin-reticulum to 

 form niielei. Special condensations of the 

 linin-filaments occur to form such structures 

 as the cffilenterate mesogloea and basement 

 membranes in general, on the surface of 

 which the nuclear nodes arrange themselves 

 to form epithelia. Skeletal structures, from 

 the radiolarian shell, the sponge spicule and 

 the coelenterate corallum to the vertebrate 

 supportive tissues, also form in connection 

 with it, and it gives rise to such structures 

 as the nematocysts, cilia and nerve- and 

 muscle-fibers. 



This is, in brief, a statement of the first of 

 the two main theses which the book seeks to 

 establish. It is, however, difficult to perceive 

 the necessity for such a unit as the chromid- 

 ium. It stands in quite a different plane than 

 the other infracellular units, such as bio- 

 phores, gemmules, etc., that have from time to 

 time been suggested, in that it is an inde- 

 pendent unit of such a great complexity that 

 the distinction between it and a cell, except 



