Fresh Water Algae in Vicinity of Montreal 397 



dently largely used as dumping grounds for rubbish — 

 i.e. those which contained the most nitrogenous material, 

 were very much the richest in algae. One pool in par- 

 ticular, which contained a great quantity of garbage, tin 

 cans, old boots, etc., was evidently an ideal location for 

 the Scenodesmaceae. All the weeds in the pool and all 

 the marginal plants which hung into it were coated 

 with a thick gelatinous film composed of Desmids and 

 Protococcaceaa. 



As far as the sources of the flora of these quarry holes 

 are concerned, there is little possibility of the dissemi- 

 nation of spores by water currents, as the various exca- 

 vations are unconnected, and there is but one small 

 stream in the whole region. On the other hand, dis- 

 semination may occasionally take place by currents of 

 air bearing spores for short distances. Probably the 

 chief means of transportation are insects, birds and other 

 animals. Frogs, in going from one pond to another, 

 would readily convey spores or even filaments of alga? 

 attached to their bodies, and it has been observed by Mr. 

 C- H. Thompson 11 in a study of the "Dissemination 

 of Lemna, " that Belostoma americana, commonly found 

 flying about electric globes on the street, carries Lemna 

 attached to its body. This insect stays in the water all 

 day and flies about at night, possibly distributing algae 

 which grow in the same habitats as Lemna. 



(3) Mount Royal: 



The ponds and streams on the Mountain were by no 

 means such favourable situations for alga? as the aban- 

 doned quarries at Amherst Park. But the fact that the 

 summer of 1911 had been very long and very hot was, no 

 doubt, partly the cause of this apparent scarcity; most 

 of the small streams being dried up and the ponds 

 low. A large artificial pond in the Roman Catholic 

 cemetery, at the back of Mount Royal, was found to 

 contain a very large quantity of Microspora entangled 



