NA JURE 



25 



THURSDAY, MAY k., i.,nr,. 



THE CULL IN MODERN BIOLOGY. 

 Algcinciiie Biologie. Die Zclle unci die Gevvebe. 

 Second edition. By Oscar Hertwig. Pp. xvi + 648; 

 371 illustrations. (Jena: Gustav Fischer, 1906.) 

 Price 15 marks. 



THE volume before us appears as the second edition 

 of the author's well known treatise on the cell, 

 the first part of which was [>ublishcd so long- ago as 

 iS(|2. 



Cytology has advanced a good deal since that time, 

 and one finds a significant recognition of its wider 

 scope in the new title — " General Biology "—given 

 by Prof. Hertwig to his book. Experience is showing 

 that the larger problems connected with living things, 

 such as organisation, heredity, function, as well as 

 those abnormal reactions constituting what we call 

 pathology, are all reducible to cell problems. 



For tlie most complex living creature is resolvable 

 i[Uo groups of more or less modified cells, and the 

 laiu-r are not merely bound together like faggots in 

 a bundle, but each group, each cell it may be, in so 

 far as it is the seat of chemical or physical change, is 

 able in greater or less degree to exert an influence 

 on other individuals of the cell community. In this 

 way there arise those adjusted relationships that 

 exist between different organs, tissues, and cells 

 which we designate as correlations, and it is just 

 because of the existence of these inter-dependent 

 cellular reactivities that complex organisation has 

 come to be a possibility. 



One of the chief aims of Prof. Hertwig's book is 

 to trace the cell in its manifold variety of form and 

 its diverse conditions of activity, especially with refer- 

 ence to the part it plays as a corporate unit of the 

 organism. It is perhaps inevitable that such a task 

 should prove too great for any single writer to accom- 

 plish satisfactorily throughout, and, indeed, the pre- 

 sent work is by no means free from the faults of its 

 ambition. Some aspects of the subject are exceedingly 

 well treated, others are left comparatively untouched, 

 while in the case of yet others the standpoint taken 

 up perhaps hardly represents that of contemporary 

 tliought. The last criticism especially applies to the 

 discussion of some of the physiological attributes of 

 cell life. Again, the more recently studied phenomena 

 of apospory, apogamy, and parthenogenesis, with their 

 general bearings on the processes of maiosis and 

 fertilisation, are very scantily dealt with. The work 

 is decidedly strongest on the morphological side, 

 although even here the treatment seems to suffer from 

 want of the physiological relationships involved. 



A considerable portion of the book is occupied with 

 discussions as to the connection that may subsist 

 between the facts of cell structure and the phenomena 

 of ontogeny and heredity. Brief accounts are given 

 of the standpoints adopted and the theories advocated 

 by otlier writers, and Hertwig adds another of his 

 own, which he terms biogenesis. 



It i^ not very easy to extract the author's exact 

 position with regard to biogenesis, and nowhere in 

 NO. 1906, VOL. 74] 



tlie volume does the theory appear to be summarised 

 and presented in a succinct and complete form. But 

 the doctrine it seems to embody is that development 

 and specialisation of function, with the corre- 

 sponding segregation of structure, are due to the corre- 

 lative action of the parts on one another coupled with 

 the influence of agencies operating from without — i.e. 

 of the environmental conditions. It is this speculative 

 part of the treatise, suggestive and interesting as it 

 is, that will probably provoke the greatest antagonism. 

 Hertwig is a thorough believer in the inheritance of 

 acquired characters, though it seems not improbable 

 that many will dissent from the interpretations he 

 puts on cases that he apparently regards as critical 

 ones. 



The example of the supposed inheritance of 

 Immunity against the poisonous action of ricin, shown 

 by Ehrlich to occur in the case of the offspring of 

 mice under certain conditions, can hardly be accepted 

 as satisfactory evidence of the " inheritance of 

 acquired characters " as the phrase is critically under- 

 stood. Indeed, it seems to break down altogether 

 when the conditions under which it may be observed 

 are examined and analysed. Mice are excessively 

 sensitive to the effects of ricin, very minute doses 

 being sufficient to bring about the death of the animal. 

 But by repeated inoculation of sublethal doses of the 

 poison a mouse may reach a state of immunity against 

 the action of a quantity far greater than that which 

 normally proves fatal. The offspring of female 

 immunised mice are themselves also immune, at least 

 during early life, whereas the young resulting from 

 a cross between an immune male and an ordinary 

 female do not exhibit the transmission of the 

 "acquired character." In other words, the trans- 

 mission is confined to the female side. It is evident, 

 however, that such a case is really of no value what- 

 ever as evidence of transmission of acquired characters 

 in the proper acceptation of the term. For it is 

 manifest that the young animal during the whole of 

 its existence in utero has been directly exposed to 

 influences that ought to confer immunity upon it, 

 apart altogether from any question of " trans- 

 mission." Furthermore, it might well be that the 

 bulky protoplasm of the es;g, irrespective of the 

 maternal influence after conception, may have been 

 affected without any disturbance of the hereditary 

 mechanism, and, indeed, Hertwig himself admits as 

 much. 



The case of certain Lepidoptera is more difficult of 

 satisfactory explanation, although the evidence would 

 probably be insufficient to convince an opponent. 

 Some of these insects respond to different climatal 

 conditions by the production of different colour- 

 patterns on their wings. Now if the pupse of some 

 species {e.g. Arctia caja) be subjected to cold, the 

 " cold " form of imago will appear, and if the fertile 

 eggs of such " cold " forms be raised under warmer 

 conditions, a small percentage of the perfect insects 

 thus produced will retain the characters of the " cold " 

 form. Hertwig dissents from the explanation, sug- 

 gested by Weismann, that the eggs themselves may 

 have been affected whilst still in the body of the 



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