16 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



9. It may be well before we proceed further, to test the 

 practical value of the definition in one or two anomalous 

 instances. a. Suppose, for instance, the student after a few 

 hours rain, goes out into the open air, and sees the gravel and 

 short grass strewed with gelatinous puckered olive-coloured 

 masses, of which he perceived no trace a few hours before : 

 his curiosity is excited and he is anxious to ascertain the 

 nature of the production. Externally it presents no marked 

 differences, and within it seems to consist of a uniform jelly, 

 without anything to make him suppose that it can be a mass 

 of eggs. He examines it imder the microscope, and he 

 finds that it consists of necklace-like chains of pellucid 

 granules immersed in jelly of no definite structure. Some of 

 these are larger then the others. He finds after a time that 

 they change colour and increase considerably in size, though 

 still retaining a regular outline ; presently, the matter con- 

 tained in their cavity becomes organised, and a new neck- 

 lace of spores is contained within it ; in fact, he has a young 

 repetition of the perfect plant, requiring only extension of 

 parts to assume completely its size and aspect. This answers 

 to the first part of the definition, but the plant does not ger- 

 minate as described ; he can discover no sexual indications, 

 though germination does not take place by the protrusion of a 

 filament, and the protoplasm of the cell at once gives rise to a 

 new plant. He believes it to belong to the vegetable kingdom, 

 and he feels that he has hit upon one of those exceptional 

 cases which defy mathematical accuracy. But still he has 

 no doubt about the matter. The plant is nostoc commune, a 

 widely -distributed Alga, bordering very close on the gelatinous 

 Lichens, b. He is again attracted by some little pearl-like 

 bodies upon a decayed stick ; he carries it home with a view 

 to examination, and the bodies have lost their soft consistence, 

 and present little skinny bags filled with elastic fibres and 

 dust. He finds these elastic fibres to be most beautifully- 

 constructed spiral vessels, with several helices curiously and 

 regularly twisted within them. He wonders to find such 

 vascular cells in a plant which presents no indications of 

 leaves or stem. On closer examination, he finds that the 



