34 Prof. Marshall Ward. Experiments on the [Feb. 16, 



easy to wash a perfectly even layer of spores over the insolated agar 

 or gelatine. Further, a critic might object that sowing spores on the 

 upper surface only of the insolated agar might yield negative results, 

 because the light-action does not extend through the entire thickness 

 of the plate, or because some volatile body is formed which is 

 washed off with the sowing. 



My new procedure is as follows : — I make, for in standee, two plates 

 of dried spores only, and two of agar only, all as before. I then 

 expose one plate of each kind, and keep the others in the dark. 



After exposure I remove the stiff and moist film of non-exposed agar 

 from its own plate, and superpose it on the exposed film of dried spores 

 in situ. Reciprocally, I remove the film of exposed agar, and superpose 

 it on the non-exposed film of dried spores. 



This prevents any wash or displacement, and ensures at the same 

 time that the agar shall present in contact with the spores that face 

 which was next the source of light. 



So far I have been unable to observe any appreciable effect on the 

 agar, though the dried spores exposed for an equal period are killed 

 in abundance. Whether exposure to more intense sunlight will make 

 it necessary to modify this must await experiment. 



Preliminary Results with the Spores of Fungi. 



Results substantially the same as the above are obtainable with 

 other Schizomycetes, but it was interesting to see whether anything of 

 the kind occurs with the spores of true Fungi. The time of year has, 

 for many reasons, been unfavourable for very numerous experiments, 

 but the results so far are extremely encouraging, and should, I think, 

 give a stimulus to close enquiry into the whole subject. 



I have so far employed the following species : — Penicillium crus- 

 taceum, Aspergillus glaucus, Botrytis cinerea, Chalara mycoderma, 

 Oidium lactis, Nectria cinnabarina, Mucor racemosus, Saccharomyces 

 pyriformis* and a " Stysanus" conidial form met with some months 

 ago as a saprophyte on Pandanus. 



On making agar and gelatine plates of these as before, I have 

 obtained positive results with Oidium (5 cases), Chalara (1 case), 

 Saccharomyces (4 cases), Stysanus (2 cases), and negative results with 

 Aspergillus (5 cases), Penicillium (2 cases), Mucor (2 cases), Nectria 

 (4 cases), and Botrytis (2 cases). 



It seems worth noting that, in all the forms which have given me 

 a positive result right off, the spores, as seen in masses, are either 

 hyaline and colourless, or, in the case of the Stysanus, with a faint 

 tinge of buff ; whereas those which gave negative results are either 

 of some very pronounced colour, as Aspergillus, Penicillium, and 

 Nectria, or (Jslwor and Botrytis) of a dull, yellow-brown hue. 



