February 22, iqooj 



NATURE 



;87 



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fusion of the two nuclei is delayed, the male pro-nucleus 



as it grows and gradually assumes a less dense appear- 

 ance, approximates more and more in its staining reac- 

 tion to that of the female pro-nucleus. Nevertheless, it 

 might also be argued that the very state of dense aggre- 

 gation implies a chemical difference, especially when it 

 is recollected that growth perhaps involves much more 

 than mere expansion of bulk. 



But it must not be supposed that the evidence adduced 

 is everywhere immediately favourable to the author's 

 standpoint. There are, in fact, many anomalies, espe- 

 cially in the case of certain basic dyes, which require to 

 be cleared up before Dr. Fischer's views can command 

 universal acceptance. It is, however, as has been 

 already said, impossible to do justice to this part of his 

 book within the limits of a single article. But as the 

 facts adduced will be largely new to most cytologists, it 

 has been thought best to utilise the available space in 

 pointing out a few lines of the argument rather than, by 

 venturing on detailed criticism, to trespass on the domain 

 of the chemist or physicist. 



By no means the least interesting part of the book is 

 that devoted to an inquiry into the origin of cell- 

 structure, spindle-fibres, centrosomes, and the like. As 

 regards the spindle-radiations, the results of some re- 

 markable experiments are detailed, and these are quite 

 startling owing to the apparent fidelity with which certain 

 of the most characteristic features of cellular activity 

 have been successfully imitated. Other investigators 

 have produced, ere now, appearances resembling the 

 achromatic spindle, but the figures have never attracted 

 serious attention, as the analogies between them and a 

 protoplasmic structure appeared to be too feeble. In 

 the present case, however, it is very different, since the 

 materials employed are akin to those which exist in the 

 cell. 



By injecting elder-pith with sundry colloids (albumen, 

 albumose, &c.), and then treating sections of the pith 

 with various fi.xatives,'the author succeeded in obtaining 

 spindle structures closely resembling those exhibited in 

 a preparation showing karyokinetic figures. Not only 

 t his, but it has been found possible to ascertain at least 

 some of the conditions which are necessary to their 

 formation. 



In the first place, there must be present in the cell 

 some foreign indifferent body which may serve as a 

 centre from which the radiations may start. Such a 

 body is often provided in the dead but persistent frag- 

 ment of the original cell-nucleus. Secondly, the pre- 

 cipitating action of the reagent must be slower than 

 its penetrative power — it must have completely satu- 

 rated the fixable substance as far as to the foreign 

 body, before the physical change of precipitation 

 sets in. Unless these conditions are both complied 

 with, no radiations will arise. The importance of 

 the second point at once becomes apparent when one 

 recollects the emphasis laid on rapidity of penetration as 

 one of the essentials of a good "fixative," and an analogy 

 between the first condition and the origin of spindle 

 fibres is seen in those multipolar spindle? associated with 

 large heterogeneous bodies in the cell protoplasm, which 

 were first pointed out by the present writer in 1893, and 

 which have since been confirmed by Mottier and many 

 NO, 1582, VOL. 61] 



other investigators. Similar Results were also obtained 

 by allowing fixatives to diffuse from capillary tubes into 

 the fixable proteids ; the radiations then started from the 

 surface of the concentrated drop of fi.xative in such a way 

 as to simulate the appearance of an attraction sphere. 



The author exercises an admirable restraint in insti- 

 tuting comparisons between these results and those 

 observed In preparations of cells, but it must not be for- 

 gotten that there is reason to believe that substances 

 very similar to, if not identical with, those employed by 

 him do really exist at least in the killed cell. 



Naturally much is still left obscure. Why, it may be 

 asked, should the precipitates only take the form of 

 radiations during mitosis? If we attempt to frame an 

 answer temporarily satisfactory on chemical or even 

 microchemical grounds, we should have to trek into 

 regions far outlying the limits of our present knowledge. 



A discussion of cytological phenomena and of the 

 various theories of protoplasmic structure and its sup- 

 posed mechanism, occupies the remainder of the volume. 

 The centrosome in particular comes in for a lengthy 

 criticism, especially as regards those alleged for the 

 higher plants. The author, on good grounds, concludes 

 that these are merely cast out nucleoli, or, at any rate, in 

 no sense to be regarded as special cell organs. He points 

 out the fallacies which have led to the obscuring of the 

 true issues in the past, and he treats the well-known case 

 of Lilium with special severity. 



It will be apparent that Prof. Fischer's book is not only 

 startling from the novelty of its contents, but it is even 

 almost revolutionary in its tendencies. But the cytologist 

 need not be unduly alarmed, nor fancy that all his 

 tenderly nurtured theories must of necessity dissolve 

 forthwith into vapour. Probably much of the " structure," 

 which was believed in by the extreme adherents of the 

 particulate school may turn out to be due to post-mortem 

 effects, and to possess no counterpart during the life 

 of the cell ; but the broad distinctions of cytological 

 structure will still hold good, even though they may not 

 be able to support the weight of the theories that have 

 been erected upon them. The chromosomes, the spindle- 

 fibres, the centrospheres (where apparent) all represent 

 definite facts of protoplasmic activity, although the con- 

 clusions which have been drawn respecting them may 

 stand in need of revision. But it is well that we have 

 been thus recalled to examine once again, and more 

 minutely than heretofore, the very foundations on which 

 our knowledge of cell phenomena rest. Diligenter 

 explorata principia ponantur. J. B. FARMER. 



RESEARCH IN PREVENTIVE MEDICINE. 

 Transactions of the Jenner Institute of Prer>entive Medi- 

 cine {late British Institute of Prex'entive Medicine). 

 Second Series. Edited by Allan Macfadyen, M.D., 

 B.Sc, Director. Pp. xv -f 253. (London : Macmillan 

 and Co., Ltd. New York : the Macmillan Company 

 1899.) 

 TOURING the last year the Jenner Institute of Pre- 

 -»— ' ventive Medicine has passed through a most 

 notable phase of evolution ; with it has become associ- 

 ated the name of the father of modern preventive 

 medicine, whilst its sphere of usefulness has been 



