592 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



the folds, but these are to be regarded as originating merely as a result 

 of tbe formation of the ridges. Four interradial insinkings of ectoderm 

 arise in the peristome, and give rise to muscle-fibres which lie at either 

 side of the supporting lamellae of the gastric ridges. Thus, therefore, 

 in regard to the most keenly disputed points, the research confirms the 

 older authors rather than Goette. 



Protozoa. 



Studies on Protozoa.* — S. Prowazek has continued his observations 

 on this subject, the present paper including discussions on certain general 

 topics. In regard to the reproduction of Ehizopods, a prolonged series of 

 observations on many different forms yielded very few instances of con- 

 jugation as distinct from ordinary plastogamy. In consequence the 

 latter phenomenon must be regarded as of great importance in testaceous 

 Ehizopods. In Euglypha alveolata at least during the process a fragment 

 of protoplasm is often left in the empty shell, which mu6t be regarded 

 as a reduction phenomenon. In general the reproductive phenomena of 

 the Testacea may be summarised as follows : — Periods of very active 

 division come to a close with a division into an abortive and an active 

 individual. This division is followed by copulation, which has only 

 been occasionally observed, and differs in its details in the different 

 genera. It would appear that at times, especially in autumn, it may be 

 followed by the formation of swarm-spores. Plastogamy is much more 

 frequent than copulation, and has also been seen in the Foraminifera. In 

 regard to the formation of pseudopodia, the author finds that the first 

 movement occurs in the ectoplasm, the endoplasm becoming involved 

 later. At first there is a sharp line of demarcation between the two 

 layers, but later this disappears either suddenly or slowly, the endoplasm 

 appearing to yield something to the ectoplasm. While the plasmic con- 

 tents of pseudopodia closely resemble those of the ordinary cell-plasm, 

 the cilia and flagella show striking differences from the cell-plasm. The 

 paper includes a discussion of some other physiological characters of the 

 Protozoa, and a description of two new forms. 



Reactions of Protozoa. — Mr. Herbert S. Jenningsf has had reprinted 

 a lecture delivered at Woods Holl on the reactions of Paramecium and 

 other ciliated Protozoa. The lecture gives a general account of the 

 various experiments made by the author, J but it merits special notice 

 as a clear and concise statement of the author's researches, and the 

 conclusions based upon them. 



In another paper,§ the same author discusses the points at issue 

 between himself and Mr. W. E. Garrey in regard to the reactions 

 of the Protozoon Chilomonas to organic acids, and concludes that the 

 differences are largely differences of nomenclature and of point of view. 

 Thus the phenomenon described by Garrey as chemokinesis, that is the 

 retreat of the organisms from an area containing weak acid, is similar to 

 the motor reflex of Paramsecium, due weight being given to the difference 

 in the activity of the organisms. Again, the phenomenon described by 



* Arbeit. Zool. Inst. Wien, xii. (1900) pp. 243-300 (2 pis.), 

 t Biol. Lect. Woods Holl, 1899. Lecture VII., pp. 93-112. 

 j Cf, this Journal, 1899, p. 495. 

 § Amir. Journ. Physiol., iii. (1900) pp. 397-403. 



