256 



Prof. H. C. Bastian on Heterogenetic 



[Mar. 21, 



to Fungus-germs ; whilst in a similar infusion prepared at 120°-130° F., 

 the embryonal areas, which seem at first to be in all respects similar, break 

 up into actively-moving Monads. It remains for us to see what changes 

 may take place in the pellicle that forms on an infusion or maceration pre- 

 pared with cold water (60°-70° F.). 



Before passing to a description of these phenomena, however, I will de- 

 scribe the mode of origin of the embryos of some organism whose real nature 

 is unknown, the final stages of its development not having been traced. 

 So far as they were seen, the stages were of a very positive character. 



I have observed these early stages in two different infusions ; but in each 

 case, after a certain stage of development had been achieved, no further pro- 

 gress seemed to be made for about two days ; and then the pellicle unfortu- 

 nately broke up and sank to the bottom. The arrest of development may 

 therefore have been due in both cases to some morbid quality of the pellicle 

 itself. These organisms were observed in the middle of the mouth of 

 April (1869), in an infusion of turnip-leaves, which had been prepared 

 fourteen days previously. All stages of development could be seen in dif- 

 ferent parts of the pellicle. The new organism first manifested itself by the 

 presence (in a uniformly granular layer) of an aggregation of 8-20 larger 

 and more refractive particles ; these were then gradually marked off from 

 the surrounding granules by a thin but distinct bounding line, whilst the 

 contained granules increased in size. At a later stage the containing sphere 



Fig. 6. — Mode of Origin and Development of an Embryo of uncertain 

 nature. ( X 800.) 



was seen to have grown larger (fig. 6, c), and the granules had assumed a 

 crescentic arrangement ; whilst on their concave side there was a tolerably 

 large refractive globule, about j-gJW' in diameter, which exhibited the 

 most distinct oscillations and more or less extensive to-and-fro movements 

 in the otherwise clear central space. In other specimens this central 

 spherule had become even larger, and the granules had closed round it 

 more equally, so as to leave a broad space between the central mass and 

 the thin walls of the containing sphere (d). The measurements in this stage 

 were found to be as follows : — containing sphere -g- oVtf"» central nuclear- 

 like body x"oiW» an ^ surrounding mass of granules -g-oVo" i* 1 diameter. 

 Afterwards the central nuclear-like body and the granular mass seemed to 

 become lighter in co^ur, — the former still exhibiting its slow oscillating 

 movements ; whilst the latter had much increased in size, so as more nearly 



