198 



THE AMERICAN MONTHLY 



[October, 



erations. If the reader will refer 

 once more to that portion of Prof. 

 Rogers' article printed on page i66, 

 he will understand the nature of the 

 test proposed, and the interests at- 

 tached to the results of such an ex- 

 amination. We hope, and believe, 

 that at the next meeting of the A. A. 

 A. S. a committee will be appointed 

 in accordance with the suggestions 

 already referred to. 



o 



Intracellular Digestion of 

 THE Lower Animals. — In a recent 

 number of Zoologischer Anzeiger, El 

 Metschinikoff has an interesting arti- 

 cle on this subject, which, however, 

 is largely a criticism of the opinions 

 of another author. 



Although it has long been known 

 that some of the lower animals can 

 take nutritive particles into their in- 

 testinal cells, the whole question of 

 intracellular digestion has been taken 

 up systematically only during the last 

 few years. The older observations on 

 the intracellular digestion of the lower 

 Metazoa remained isolated and were 

 soon forgotten. Led by the facts of 

 embryology to the assumption that 

 in the original condition the digestive 

 organ must produce a solid, intracel- 

 lular, digestive parenchyme, the 

 author has studied the digestive pro- 

 cess of the lower organisms since the 

 year 1877, and proved that in the 

 turbellaria and coelenterata (includ- 

 ing the sponges) intracellular diges- 

 tion is general. Taking the results 

 obtained with Protozoa, it was ob- 

 served that the processes of digestion 

 in some of the lower Metazoa are the 

 same as in the infusoria. Experi- 

 ments were made with carmine, 

 striated muscle, the yolk of hard- 

 boiled eggs, starch, etc., but these, 

 while they could be readily observed 

 within the animals, were not found to 

 be readily assimilated ; but by feed- 

 ing with natural foods, digestion 

 was easily observed. An excellent 

 organism for such observations is a 

 Ctenophora, " in which one can follow 

 the entire process, from beginning to 



end, /. e., to the formation of the 

 partly crystalline concretions within 

 the vacuoles, in one and the same 

 individual." 



This subject can only be studied 

 microscopically. " The physiologi- 

 cal-chemical method, however im- 

 portant it appears to be, cannot be 

 used in the investigation of such 

 minute objects as Protozoa, and cells." 

 Fortunately, however, it can be satis- 

 factorily studied with the microscope ; 

 and we suggest this as a good, and 

 almost new, field for any one who will 

 undertake the labor of investigation. 

 It requires only patience and careful 

 observation to reach interesting and 

 valuable results. Prof. Leidy has 

 studied the process of digestion 

 among some of the rhizopods, and 

 no one can read his descriptions of 

 it without finding them very interest- 

 ing. 



Mounting Histological Speci- 

 mens. — It will probably be a long 

 time before histologists will be agreed 

 as to the best medium for mounting 

 their specimens. Mr. T. Charters 

 White, M. R. C. S., in the course of 

 a very practical article " On the In- 

 jection of Specimens for Microscopi- 

 cal Examination," read before the 

 Quekett Club, used these words : 

 " You will, in the subsequent ex- 

 amination of it [the specimen pre- 

 pared], be able to determine how 

 much is the result of the mounting 

 medium in which I have placed it ; 

 for my part, I believe it is entirely 

 due to this that not only the villi but 

 the Lieberkiihnian follicles are most 

 clearly shown with the capillary ves- 

 sels coursing all through and around 

 them ; and I must aver that had this 

 specimen been mounted in balsam, 

 or dammar, every detail would have 

 been sacrificed. I consider balsam 

 to be the greatest bane histology has 

 to fight against." 



The mounting medium referred to, 

 was glycerin and camphor-water. 

 Other histologists condemn glycerin 



