150 Eni))iisa Muscae versus Musca Domestica L. 



the coverglasses underneath. Spores were freely shed and collected 

 absolutely pure. 



The usual methods used in spore cultures were then employed, 

 but the results were not satisfactory. I then used for a medium various 

 animal fats — a droplet of butter, of dripping, of lard, etc. These were 

 exposed to the spore bombardment, but no more appreciable results 

 were obtained. Moreover, these substances were found to be very 

 unsuitable for microscopic use owing to their annoying refractive 

 indices and their opacity. How much more unsatisfactory must the 

 egg yolk medium — stone hard, no doubt, from the method of treatment 

 given by Mr Hesse — have proved itself. I also tried sterile asparagus 

 tips — mainly because of the known lecithin contents of this plant — • 

 but no satisfactory results were achieved on it either. 



I then obtained interesting results from the use of a mineral fat, 

 i.e. common vasehne, as used for ringing shdes in hanging drops. This 

 medium was sterile to begin with and made beautiful clear hanging 

 drops or surfaces. A small quantity was placed with a scalpel on a clean 

 coverglass and gently heated until evenly spread like a film over the 

 coverglass. When exposed to spore-shedding, the number of spores 

 desired thereon was easily adjusted by the removal of coverglasses 

 after one, two, three or more minutes' exposure. The coverglasses 

 were then inverted on hollow ground slides and ready for examination. 

 - To obviate any misunderstanding, here let me remark parentheti- 

 cally that, in the description following, I am not detaihng the result 

 (^ any one particular experiment, but am summarising the nett results 

 of some hundreds of observations. 



Germination began very shortly in every instance. The plasmatic 

 mass which surrounds the spore when shot from the conidiophore 

 appeared to remain in a liquid or semi-hquid form; it never showed 

 the wrinkled appearance generally observed, and so often figured. The 

 first symptoms of active life appeared about one hour after the spores 

 had been shot on the medium. Never at any time did the original 

 spore produce a germinal tube; at first there appeared something 

 very much like a germinal tube in the shape of a small " exdentation " 

 of the cell wall of the mother spore. This gradually elongated, but 

 assumed, from ten to fifteen minutes later, a flask or clubshaped appear- 

 ance. About an hour later it was recognised with certainty as a second- 

 ary spore, the nucleus of the first spore having taken up its position 

 in the now forming secondary spore. As this spore grew, it, together 

 with the mother spore, presented a dumb-bell shape. Where joined 



