450 SUMMARY OF CURRENT RESEARCHES RELATING TO 



unknown factor in cell-metabolism, from which recovery is autonomous. 

 A cycle extends over a varying number of rhythms, and ends in extinc- 

 tion of the race unless it is " rejuvenated " by conjugation or changed 

 environment. Seasonal and temperature changes have no apparent in- 

 fluence on the cyclical fluctuations of vitality. Variation in temperature, 

 however, undoubtedly affects somewhat the daily rate of division, if not 

 directly at least through the food supply. The physiological and struc- 

 tural changes which appear at periods of low vitality are described. It 

 is also noted that under varying conditions structural modifications 

 occur which are in no way abnormal, and that those observed most 

 frequently in " wild " Infusoria are not so constant as is usually 

 supposed. 



Leptophrys.* — W. A. Kepner describes a form which, except for the 

 absence of nuclei and the variable size of the vacuoles, corresponded 

 with Leptophrys ehgans, described by Hertwig and Lesser. It is 

 suggested that these investigators mistook ingested monads for nuclei. 

 Locomotion is effected by more or less active amoeboid movements. " An 

 active large individual tosses itself about very much as a cloud of smoke 

 is distorted by a current of air." After the animal gorges itself with 

 diatoms, desmids, and monads, it encysts. Division into two was 

 observed, but no trace of a nucleus was seen. As Penard suggested, it 

 seems likely that Leptophrys is but a synonym for a species of Vampyrella. 



Studies on Peridinese.f — Geza Entz, junior, gives an account of 

 the Peridinese captured in the plankton of Quarnero and Quarerola, 

 enumerating fifty-nine forms, and discussing the variations of species of 

 Geratiwn. He gives a detailed account of the plates of Phalacroma 

 jourdani and Ceratocorys horrida, and shows the homologies of the plates 

 in Phalseromese and Ceratias. The process of division in these families 

 is also discussed. 



Identity of Surra and Mbori. $ — A. Laveran has shown that the 

 Trypanosomiasis which Cazalbon called Mbori, and which chiefly attacks 

 dromedaries in French Soudan, is due to the same parasite as Surra 

 {Trypanosoma evansi). Structurally, the two Trypanosomes are the 

 same, and animals immune to Surra are immune to Mbori, and vice versa. 

 The Trypanosome of Mbori is, however, slightly less virulent than that of 

 Surra. 



Parasite of Acute Exanthema. §— J Siegel has found in the whole 

 group of so-called acute exanthematous diseases a flagellate parasite, 

 with naked body, at least two distinct nuclei, and 1-3 flagella. The 

 multiplication occurs by repeated division of the nucleus (sporulation), 

 and also by longitudinal division. In Vaccinia the parasites not only 

 occur in the affected parts of the skin, but swarm in the blood. Guarnieri 

 has given the name Cytorrhyctes to these organisms. 



* Amer. Nat., xl. (1906) pp. 335-42 (8 figs.). 



t Math. Nat. Ber. Ungarn., xx. (1905) pp. 96-144 (66 figs.). 



X Comptes Rendus, cxli. (1905) pp. 1204-7. 



§ SB. Ges. Nat. Preunde Berlin, 1905, pp. 195-7 (1 fig.). 



