84 DIVISION 1. -GENERAL MORPHOLOGY. 



its sporangiophore and adheres by means of the gelatinous layer to foreign bodies, 

 while the spores swell to their full extent and are disseminated. The sporangio- 

 phore in these species 1 is a cell sunn- millimetres in length, cylindrical in its middle 

 portion, but inflated in its lower part and in its upper part especially just beneath 



the sporangium. It becomes more and more turgescent after the spores have 

 matured and causes abjection of the sporangium by means of the mechanism 

 described on page 72. The separation takes place in the line of an annular fissure, 

 which is close beneath the insertion of the outer wall of the sporangium and is seen 

 before the sporangium is flung off as a fine sharply marked line on the wall (Fig. 38). 

 The delicate wall of the lower portion of the sporangium is ruptured at the moment 

 of abjection, being struck by the ejected fluid, and thus the swelling of the gelatinous 

 layer investing the spores is secured. 



The sporangium is sometimes abjected with considerable force. The sporangia 

 of Pilobolus oedipus, in which species, according to Coemans and IJrcfeld, the greatest 

 amount of force is exerted, are thrown, as we learn from the former authority, to a height 

 of more than 1.05 M. The process, as Coemans has also proved, is greatly 

 dependent on the amount of light. Under favourable circumstances the development 

 of the sporangiophore begins at midday or in the afternoon ; it is completed and the 

 sporangia and spores are also formed during the night, and the sporangium is thrown 

 off during the following morning at an earlier or later hour according to the greater 

 or less amount of light. Exclusion of light does not entirely prevent abjection but 

 may delay it 12-15 hours. P. oedipus shows this sensitiveness to light and the 

 normal periodicity to a less extent than P. crystallinus. We must not enter further 

 in this place into the connection between these phenomena and the very strong positive 

 heliotropism of the sporangiophore. 



The increasing turgescence of the sporangiferous cell before abjection, assuming that 

 the superficial extent and elasticity of the membrane remain the same, may be 

 caused either by increasing osmotic absorption of water on the part of the sporangiferous 

 cell itself, or by the forcing of water from the mycelium into the passive sporangiferous cell, 

 or by the combined operation of both these agencies. In my first edition I assumed 

 that the latter of the two was the only operative cause, because a drop of water which 

 increases in size is often seen to issue after abjection from the open sporangiferous cell 

 before it finally collapses. More exact measurements are required for the confirmation 

 of this view. 



Section XXI. The spores produced in asci and those of Protornyces 

 macrosporus are set free in one of two ways according to the species; either by 

 ejection * (Ausschleuderung, Ejaculation) or by solution or gelatinous swelling (Auflosung, 

 gallertige Verquellung) of the as< i. 



The first process, the process of ejection, is found only in the 1 ase of spores 

 which in inn, illy attain their full development inside the asctis. As they advance 

 towards this state, the protoplasm around them and the glycogen-mass subsequently 

 formed constantly diminish in quantity, being doubtless used to a great extent as 

 material for the formation of the spores. We are not at present in possession of more 



1 Coemans in Mem. cone, de l'Acad. royale <le Belgiqne, XXX. — J. Klein in Pringsheim's 

 Jahrb. VIII, p. 305. — Brefeld, Schimmelpilze, land IV. — Van Tieghem, Mucorinees. See also the 



literature cited in sections XLI-XLIV. 



1'jection' and 'ejection' have been adopted as renderings of 'Abschleuderung' and' Ausschleu- 

 demng,' the throwing off or throwing out with force of spores from the sporogtnous structure. 



