CHAPTER III.— SPORES OF FUNGI. — GERMINATION. 



Ill 



soon comes to an end ; it elongates for a little while and then abjoints acrogenously 

 at the expense of its protoplasm a small number of spores unlike the mother-spore, 

 and itself soon dies away. The product of germination in this case bears the name 

 of promycelium which was given to it by Tulasne, and the abjointed spores are 

 termed sporidia (Fig. 55 A, B, Fig. 56). Both types of formation of germ-tubes are 

 always peculiar to certain species and to certain forms of spores, on which point 

 further remarks will be found in Chapter V ; both behave alike in those first 

 stages of their development with which we are concerned in this place. 



Taking the simple non-septate spore-cells first, we find the simplest formation 

 of the germ-tube among swarm-spores. As soon as they have come to rest and are 

 provided with a membrane, they grow out at one or two or even more points into a 

 cylindrical tubular process the membrane of which is the immediate continuation of 

 the membrane of the spore (Fig. 53.) In most of the non-motile spores the 

 proceeding is essentially the same, but with this difference, that the tube is covered 

 only by a delicate continuation of an innermost layer of the spore-membrane. It is 

 uncertain whether in the case of these spores the whole of the spore-membrane is 

 ever prolonged as the covering of the tube ; 

 even where the spore-membrane before ger- 

 mination is delicate and without obvious separ- 

 ation into endosporium and episporium, the 

 delicate wall of the germ-tube may often be 

 clearly seen to be continuous with the layer of 

 the inner surface of the spore-membrane, as 

 in Acrostalagmus, Penicillium, &c. Even where 

 an endosporium is stout its whole substance is 

 not extruded to form the membrane of the 

 germ tube, but only its innermost lamella, as in 

 uredospores. The advancing germ-tube breaks 

 through the outer layers where the episporium 

 is strongly developed, causing them to open by 



valves or perforating them, and this either at spots not previously marked out by 

 any special structure, or in places where pits were formed before the spores had 

 matured and which were spoken of above as germ-pores. In a few cases the 

 development of the germ-tube and the swelling of the inner part of the spore 

 associated with it cause the layers of the episporium to break up into small pieces, 

 as in Ascobolus sp., Diplodia sp. 1 , and some others. 



In some spores with a very stout episporium and a narrow germ-pore, as in 

 Coprinus, Sordaria, and Chaetomium, the tube as it passes through the pore is a very 

 slender protuberance, but immediately in front of the outer orifice of the pore it 

 swells into a round and comparatively broad vesicle and after that grows on as a 

 cylindrical tube, which may be branched or unbranched, a mode of growth which 

 looks peculiar and has given occasion to strange misconceptions 2 , but is really 

 nothing more than a special case not deserving any particular designation. 



FlG. 56. Rhytisma Audromedae, Fr. Asco- 

 spores germinating on the surface of water. The 

 spore x is still surrounded by the original gelatinous 

 border, which has disappeared in the other two ; 

 P the promycelium, s a sporidium. Magn. 390 

 times. 



1 Bauke, Beitr. z. K. d. Pycniden. 



2 Bot. Ztg. 1866, p. 158. 



