172 SUMMARY OF CUEREXT RESEARCHES RELATING TO 



must alike be rejected as incorrect. Starting with single females, the 

 author has bred as many as sixty-four and seventy-three generations, 

 testing with great care the sex-character of each offspring. Green 

 Euglmas were used as food during these experiments, which lasted 

 about eighteen months. Hyddtina, as is well known, produces either 

 parthenogetic female eggs, parthenogenetic male eggs, or fertilised rest- 

 ing eggs, but any given female lays but one of these classes of eggs 

 during her lifetime. 



The author's experiments have led him to the conclusion that there 

 are three different types, or strains, in the Mendelian sense, of parthe- 

 nogenetic females, namely : A, females producing a high percentage of 

 females which will lay male eggs ; B, females producing a low percentage 

 of females laying male eggs ; C, females producing females which never 

 lay male eggs. A pure strain of type C was cultivated for seventy-three 

 generations, during which oOi individuals were tested and none produced 

 males. Individuals of this strain were subjected to temperature tests, 

 as well as to starvation tests, but no males were produced. 



A consideration of the whole of these results has led the author to 

 make some remarks on the nature of parthenogenesis in Hijdatina, and 

 to conclude that '• it seems not inconceival)le that the female-producing 

 females are really hermaphrodite, though the male gametes may not 

 exhil)it the orthodox form of spermatozoa." 



Tetramastix opoliensis.* — C. F. Rousselet supplies a rectified figure 

 and description of this rare Rotifer, showing that it belongs to the 

 family of the TriarthradfB, instead of that of the Anurteadge, as was at 

 first supposed. The error has been due to the fact that the creature was 

 first found in a fully contracted state only, when the two long skipping 

 spines are directed forward, apparently continuous with the integu- 

 ment. A drawing of the living animal by St. Hlava has enabled 

 the author to coiTect the error. So far, this species has been found 

 three times only, namely, by Zacharias in 181)7, in material from the 

 Oder, by Oppelu, Germany; by St. Hlava in IcSlJl), in a pond near 

 Tabor, Bohemia ; and in 1!)05 by the author, in a pool in the Matopos, 

 in Rhodesia. 



Morphology and Variations in the Wheel-organ of Rotifera.t — 



P. de Beauchamp attempts to show that the usual division of the ciliary 

 wreath of Rotifers in trochus and cingulum, almost universally accepted 

 since Cubitt introduced these terms, does not at all apply to the vast 

 majority of species, and, moreover, that this conception is incorrect, as it 

 takes too little account of the band of fine cilia (the ciliated grove) 

 which exists between the trochus and cingulum. The author considers 

 this band to be of prime importance in the morphology of the ciliary 

 ^vreath, and regards the larger cilia of the trochus and cingulum as only 

 the modified outer margins of this band in a few families, which, 

 unfortunately, have always been taken as the types of the whole class. 

 After giving some exact figures and descriptions of the ciliary AVi-eath 

 of eight species of Ploima, the author proceeds to construct a diagram 



* Journ. Quekett Micr. Club, ser. 2, ix. No. 59 (1906) pp. 431-2 (1 pL). 

 t Arch. Zool. Exper., ser. 4, vi. (1907) pp. 1-29. 



