MYCETOZOA. 135 



be discharged into the surrounding water by the rupture of the 

 vacuoles. 



The observation of the ingestion of bacteria by swarm-cells is of 

 great interest in connection with the remarkable discoveries of 

 Metschnikoff with regard to the white corpuscles of the blood ; he 

 has shown, and his investigations have been confirmed by other 

 eminent workers on the Continent, that the white corpuscles or 

 leucocytes devour the bacteria and microbes which are associated 

 with diseases of various kinds which find their way into the 

 tissues, not only of ourselves but of all animals down to the minute 

 transparent water fleas which abound in our ponds. It was with 

 these water fleas that some of MetschnikofFs experiments were 

 carried on. We are now told that our health depends on the 

 vigilance of the lencocytes in seizing on these invaders and absorb- 

 ing them in a manner analogous to that we see performed by the 

 swarm-cells of Mycetozoa. 



Before proceeding to describe the sporangia or ripe fruits, if we 

 may so call them, which were shown at the meeting of the Club, 

 it may be well to glance at the remarkable process which takes 

 place when the plasmodium changes into these forms. It has for 

 months, perhaps, been wandering among dead vegetable matter, 

 breaking it down by its powerful disintegrating properties and 

 doing its part to convert it into wholesome nutritive material to be 

 appropriated by other growths. When the time comes for this 

 stage to end it crawls out of its hidden recesses to some situation 

 where the spores, when formed, should be most favourably placed 

 for their ultimate distribution. The plasmodium which inhabits 

 heaps of rotting leaves spreads over the under surface of the upper 

 layers -where the sporangia will be protected from the rain but will 

 be within reach of drying winds ; that which permeates decayed 

 stumps emerges at some spot where it is sheltered from the sun 

 and can slowly ripen in a moist atmosphere. Some species will 

 crawl up the stems of ferns or grasses to positions of more exposure, 

 but these are usually of a kind which mature very rapidly. The 

 Mycetozoa are divided into two divisions one in which the 



