168 



A NEW AND PARASITIC 



A special interest appears to attach to this species of Choanephora both beca 



of its capacity for parasitic 

 the genus to \ 



d because it contributes additional evidence that 



Inch 



it belongs is 



of 



generalised type sho 



special points 



of affinity to many other phycotnycete 



d 



higher 



Parasitism has, of course 



* 



long 



been 



recogn 



sed 



fung 



as 



occurring 



am ong 



fmuri in the genera Piptocephalis, Syncephalis and Chsetoclad 



zygomycete 

 but this would appear 



to be tho first instance 



the 



of a zygomycete as a true parasite 



pi 



host has been 



orded. It is somewhat difficult to dete 



the parasitism or tho saprophyt 



should b 



regarded 



as 



facultative 



If 



whether 

 we are 



tu 



pt De l>ary 



that the production of zygospores 



medium rather than 



other is tho true criterion, 



# 



the 



the 



parasirism is 



< 



facultative 



as 



ygospo 



cer- 



appear to be more readily produced in artificial media than in the tissues of 



the host plant. But it appears to be 



hat questionable whether this be a true 



terion. Oosp 



and zygospores when produced by parasitic oomycete and zygomy 



eeto organisms are in many cases not produced until after th 



de 



of the host has 



boen induced by the parasitism, which would appear to indicate that their production 



<loc 

 ind 



not 



jorrespond with the pre 

 of a fall in these and i 



of maximal nut 



fac 



th 



of vegetative growth 



>s, but is rathe 

 Similarly, in th 



case or the purely saprophytic Choanephora Cunninqhamana zygospores are never prod 



ed until comparatively late in the duration of any cult 



d 



a period wh 



nutritive properties of tl 

 abundant mycelium and 



medium have been in 

 midiiferous fructiticat: 



% 



part 



I 



pended in providii 



the 

 for 



so far as the Choaneph 



< 



ed, the true criterion of the presence of conditions f 



activity and vigorous grow 

 Choanephora Cunninghamiana 

 primarily produces nothing 



is the extent to 



d 



ssive nutritional 

 fructification is produced. 



rosa-smensis 



in its normal site on the flowers of Hibi 

 but excessive mycelial growth and conidiiferous fructifi 



tion. It is only when the tissues of the flower have bee 



zygospores make their appearance, and they also frequently occur 



n greatly decomposed that 



abundantly 



in 



or 



Hibiscus p 



th an impoverished conidial fructification in artificial cultivations in infus 



When mycelial growtn is very 



and 



fructification reaches its maxin 

 providing for maximal mycelia 

 are absent that zygosporic fructific 



al develop 



vigorous 



the conidiiferous 



and it is only when the conditions 



gro 



and fully developed conidiiferous fructification 



species of Choanepl 



begins 



to appear 



Turning 



to the second 



no one who has ever seen the enormous development which 



the mycelial system attains within the tissues of Ip 



th that which it presents in infusions 



rubro-ccerule% as compared 



entertain any doubt that the nutritional fac 



f the host-plant or of Hibiscus petals 



can 



provided by the artificial med 



tly inferior to those provided by tho living tissues of the host-plant 

 appear rarely or never to occur in the tissues of the host-plant when 



most favourable to 



But zygospores 

 conditions are 



my 



t ifi cation, whilst they occur in 



extension and enormous prod 



of conidiife 



abundance 



in 



these 



in 



are associated 



many 



rtificial 



fruc- 

 and 



fructification, which in the case of Choaneph 



t with the conidiiferous, but with the sporangic form of 



demonstrated to be 



nutritional 

 defective 



Cunningh 

 one which is associated, not with 



activity, being 



in fact the for 



zmiana can be unequivocally 

 an excess but a defect of 



of nutritive 



m 



f fructification which only appears with 



d goes on sh 



owing 



tself until the defect 



♦ V«g leichvnde Morphulogie und Biggie der l>iize, Leipzig, 



1^4, g. 414. 















