July 7, 1910] 



NATURE 



THE METAB<UJSM OF MARINE ANIMALS. 

 Die Eniiihruiig dcr W'asscrticrc und dcr Stoffliauslialt 

 der Ccwasscr. By Prof. August Putter. Pp. iv + 

 168. (Jena : Gustav Fischer, 1909.) Price 5 marks 

 (unbound). 



TWO \ears ago Prof. Putter published three papers 

 dealing with the metabolism of marine animals. 

 The thesis advanced as the result of these investiga- 

 tions m.iy be briefly summarised as follows : — the 

 nutrition of a very great number of marine animals 

 belonging to all phyla is not effected in the manner 

 characteristic of the mammal, that is, by the ingestion 

 of solid organised food, and by the subsequent diges- 

 tion and absorption of this matter bv special organs. 

 but by the direct absorption of carbon and nitrogen 

 compounds which are contained in solution in the sea. 

 The notion that many animals were really saprozoic 

 in their habits was not really a new one; most in- 

 ternal parasites, whether provided or not with an 

 alimentary canal, obviously e.xhibit such a mode of 

 nutrition ; but the hypothesis that animals living in 

 the open feed otherwise than by the ingestion of solid 

 organised food, or by the utilisation of photosynthetic 

 products elaborated by the activity of commensal 

 alga?, was a new one, and has provoked much discus- 

 sion. Putter's methods have been criticised by Henze 

 and Lohmann, and the paper now under review 

 amplifies the author's former work, and to some extent 

 meets the criticisms advanced. 



The proof of the thesis is developed along three 

 main lines. The author has studied the intensitv of 

 metabolism in a number of forms, and has found 

 that this is proportional to the unit of surface, and 

 not to the unit of mass. Therefore the relativelv 

 minute organisms which are found among the plank- 

 ton, or even those larger animals which are provided 

 with a large absorptive surface in the shape of gills, 

 ctenidia, respiratory plumes, &c., and internal diverti- 

 cula, are able to utilise the exceedingly dilute solution 

 of organic carbon and nitrogen compounds contained 

 in sea water. The intensity of metabolism is measured 

 by the o.xygen consumption and the carbonic acid 

 output, and, generally speaking, the rate of exchange 

 is, roughly, constant in animals of the same general 

 type of organisation, when it is regarded as a function 

 of the unit of surface. The divergencies from this 

 approximately constant rate are to be regarded as 

 dependent on the deviations from the usual mode of 

 metabolism characteristic of the animal group con- 

 sidered. 



The second line of proof depends on the existence 

 of compounds of carbon other than carbonates, and 

 compounds of nitrogen other than ammonia, nitrates, 

 and nitrites, in solution in sea water. From the 

 author's point of view the sea is an immense store- 

 house of dissolved food-stuff, which is utilised bv most 

 marine animals. In his first papers. Putter estimated 

 that the water of Naples Bay contained some 65 

 milligrams of organic carbon (volatile and higher 

 fatty acids, and carbohydrates) per litre. Shortly 

 afterwards Henze showed that the amount was greatly 

 over-estimated, and that the proportion of such sub- 

 stances present was so small that it lay within the 

 NO. 2123, VOL. 84] 



limits of error of the experimental methods employed 

 by Piitter. Raben, however, showed that the water 

 from the North Sea and Baltic did actually contain 

 . measurable quantities of organic carbon varying from 

 about 3 to 37 milligrams per litre. If these results 

 should be confirmed, they would back up Putter's 

 hypothesis, since the solution would then be sufficiently 

 concentrated to act as a food medium.. 



The third line of proof is much stronger, but it 

 depends on the author's estimates of the rate of 

 e.xchange of oxygen and carbonic acid in the animals 

 studied. Taking the case of plankton-feeding 

 creatures, he shows that it is, in most cases, impos- 

 sible that a sufficient amount of food can be obtained 

 from the plankton to account for the rate of meta- 

 bolic exchange. A sponge (Suberites), for instance, 

 of some 60 grams weight required about 0*92 mgrm. 

 of carbon per hour. Now taking a certain density 

 of the plankton, this postulated that the sponge would 

 have to pass some 242 litres of water through its canal 

 system in order to get the necessary food-stuff from 

 the plankton. It is quite impossible, of course, that 

 the animal can filter this volume of fluid in the time. 

 It has been shown by Lohmann that Putter under- 

 estimated the density of the plankton, and by Henze 

 that he over-estimated the concentration of the sea 

 water in carbon compounds. But when the revised 

 values are substituted, the argument is not materially 

 affected. A further instance of the same nature is 

 that of the copepod Calanus. If this animal feeds 

 exclusively on plankton diatoms it must ingest some 

 16,000 medium-sized Coscinodisci, or about ten 

 millions of Thalassiosira;, in order to account for its 

 metabolic exchange. Such figures appear to preclude 

 the possibility of an exclusive feeding on diatoms. 



It is, of course, quite probable that marine animals 

 may feed in the same way as internal parasites, by 

 absorption of dissolved food-stuff, and that this mode 

 of nutrition may proceed simultaneously with that 

 depending on the existence of an alimentary canal. 

 If the metabolism of the lower invertebrates had been 

 studied as carefully as that of the warm-blooded 

 animal, this contention might have been accepted 

 long ago. It is mainly by analogy with the latter 

 that we ascribe respiratory functions to the structures 

 called gills ; they might just as reasonably be re- 

 garded as organs for absorption of food-stuff. How- 

 ever this may be, it appears from the work now 

 noticed that the conclusions are only very probable 

 ones until the data representing the rate of exchange 

 of oxygen and carbonic acid have been critically 

 revised. The proof or disproof of the author's thesis 

 will be effected by such revision. J. J. " 



SMALLPOX AND VACCINATION IN BRITISH 

 INDIA. 



Smallpox and ]'accination in British India. By 

 Major S. P. James. Pp. xi + 106. (Calcutta : 

 Thacker, Spink and Co., 1909.) Price 75. 6d. 



AT a time when the study of tropical diseases is 

 setting its indelible mark on the history of the 

 progress of medicine, it is well to be reminded that 



