126 W. ARCHER. 



grounds for the supposition that the penetration was the 

 result of any mechanical violence during the manipulation. 



Experiments in Sowing Spores. — In order to obtain a suffi- 

 cient quantity of spores, Tulasne's method was employed. 

 The lichens were placed on plates, well moistened, and then 

 covered by the slides, upon which, after twelve to twenty- 

 four hours, a number of spores were found. The lichens 

 from which the spores were taken were always gathered just 

 previously, indeed, I took, perhaps, overmuch care not to use 

 examples which were gathered more than a day before, 

 and this with a view to avoid giving rise to the objection 

 that the small quantity of the spores obtained, or the unsatis- 

 factory results of the germination of the spores, were a result 

 of the specimens not being fresh. It is known, indeed, that 

 the germinative power of spores subsists but for a short time, 

 and also that herbarium-examj)les of lichens, ujion being 

 moistened, give oif no spores. ***** 



To produce germination the spores were placed in a moist 

 atmosphere. For this purpose a basin or deep plate was filled 

 about halfway with Avater, and in it was placed a small saucer 

 or a piece of stone or marble. Upon these objects, which 

 projected above the water, were placed the slides with the 

 spores ; and over the whole a bell-glass reaching to the water 

 in the basin, so that in this way the air of the space containing 

 tlje spores soon became moist. In other cases the same end was 

 attained by laying a sheet of glass or an ordinary plate over 

 the basin, the last for experiments on germination in the 

 dark. 



As regards the other circumstances under which the spores 

 were placed for germination, these varied according to the 

 end in view in observing the germination. For different 

 purposes, two different methods were followed, and these 

 will be separately treated: — 



I. The observation of the germination of the spores had for 

 its object to ascertain if the germinating filament produce a 

 kind of mycelium, some cells of which pass over into young 

 gonidia, as must happen if the lichens are to be regarded 

 as autonomous. 



The majority of the experiments were conducted in the 

 same way as by previous observers Avho had the same object 

 in view: that is to say, the spores were placed in a moist 

 medium. I generally left the spores upon the slides whereon 

 they were taken ; the progress of germination could thus 

 readily be examined under the microscope. Sometimes, 

 also, I placed the spores, by means of a drop of water, upon 

 pieces of bark from the same tree on which the lichen grew 



