426 PKOI". ALLMAN ON THE RECENT RESEARCHES 



mass broke up into a multitude of minute flagellate young resem- 

 bling the original parents in all points but size, 



Messrs. Dallinger and Drysdale have further made a series of 

 well-conducted observations on the capacity possessed by these 

 "monads" of resisting high temperatures, and have arrived at 

 results of great importance in their bearing on the evidence 

 adduced by the advocates of the doctrine of spontaneous genera- 

 tion. They have thus shown that while the adult form is destroyed 

 by a temperature comparatively low, the minute inactive sporules 

 which result from the fusion of two monads may survive and be- 

 come developed into the complete organism after exposure to a 

 temperature of from 121° C. (258"" Eahr.) to 140°-88 C. (300° 

 Fahr.). This, however, occurs only in the case of the inactive 

 sporules ; the young active brood into which, in one of the spe- 

 cies, the blended mass of sarcode breaks up only feebly survived a 

 temperature of 82°-22 C. (ISO" Fahr.). 



The capacity of resisting heat possessed by the inactive sporules 

 has been estimated by the authors as bearing to that of the deve- 

 loped monad an average ratio of 11 : 6. 



Haeckel records some additional observations on the structure 

 of the Eadiolaria*. He had already -f made it probable that the 

 protoplasm of these is formed by the union of many true cells. 

 As undoubted cells of the Eadiolaria he had indicated the remark- 

 able " yellow cells " and the intracapsular cells and alveolar cells, 

 Eecent observations have convinced him that the spherical clear 

 vesicles which form the most important and constant constituent 

 of the central capsule are genuine cells. He finds in them a true 

 nucleus, and he regards it as very probable that they are repro- 

 ductive cells. 



This suspicion has been since confirmed by the observations of 

 Cienkowski, who has seen the contents of the central capsule 

 in CollospJbCBra break up into monadiform masses, which developed 

 on one end a pair of cilia and escaped in the form of zoospores {. 

 The ultimate destiny, however, of these bodies remains unknown. 



It is well known that in ActinospJicBrium EicTiornii (which with 

 ActinopJirys sol and most of the so-called freshwater Eadiolarians 

 constitute the group of the Heliozoa) numerous nuclei exist in the 



* " Beitrage zur Plastidentheorie," Jen. Zeitschr. vol. v. 

 t Die Eadiolarien, 1862. 



X Cienkowski, "Uebei* Schwai'mebildung bei Eadiolarien," Archiv f. mikr. 

 Anat. vol. vii. 1871. 



