INDUSTRIAL PROGRESS DURING THE YEAR 1875. cxlv 



culiar calyx-like form. The authors state that the complete 

 detail in the development of these monads was only success- 

 fully compassed by the one twenty-fifth and one fiftieth of 

 Powell and Lealand, with diameters ranging from 2500 to 

 5000. They express a complete distrust of all observations 

 founded on successive " dips " in a quickly changing organic 

 infusion, and put no faith in observations of this sort, and not 

 conducted on the plan of keeping the same drop under con- 

 tinuous observation during all alleged transformations. From 

 their own observations on these lowly forms they are con- 

 strained to say " that not the slightest countenance is given 

 to the doctrine of heterogenesis. On the contrary, they find 

 the life cycle of a monad to be as rigidly circumscribed with- 

 in definite limits as that of a mollusk or a bird. The heat- 

 ing experiments uniformly proved that the spores resulting 

 from sexual generation have a power of resistance to heat 

 over the adult, which is greater in the proportion of eleven 

 to six on the average the very essence of the question of 

 biogenesis versus abiogenesis some of the spores resisting 

 88 Fahr. above the boiling point of water. This result 

 agrees with the experiments of Dr. W. Roberts, and later 

 of Huitzinga, who could not destroy the bacteria or their 

 germs by boiling for half an hour under a heat of 230 

 Fahr. 



In the proceedings of the Philadelphia Academy, April, 

 1875, we find a paper by Dr. Leidy upon a curious rhizopod, 

 which he terms Blomyxa vagcms. He compares it to the 

 reticular pseudopods of a Grornia separated from the body. 

 The creature moved actively, and assumed the most varied 

 forms. This curious rhizopod had already been observed, 

 especially in connection with the Diatomaceae. When, in 

 moving along the stems of conferva, it encounters a group of 

 diatoms synedra, e. g. instantly the whole mass spreads 

 out and envelops them, and for hours remains motionless, ex- 

 cept the movement of the internal granules. A partial so- 

 lution of the silica is effected in the process of digestion ; for 

 after some hours an enveloping case, partially silicious, and 

 which has formed during the interval, inclosing both rhizo- 

 pod and diatoms, is ruptured, and in one or more streams the 

 branching mass escapes, leaving the silicious case quite per- 

 ceptible, and the diatoms so firmly fused together that se- 



V 



