122 



several), which varies somewhat in size, and is sometimes in the 

 centre of the globe, sometimes placed eccentrically. Their form 

 will be seen by reference to fig. 5. 



The average diameter of the sporidia is about -s-^th of an inch. 

 Upon placing a thin section of one of the plants in water under the 

 microscope, and adding a drop of solution of iodine, the sporidia in 

 the course of a few seconds assume a more or less dark purple 

 colour, precisely similar to that produced in starch by the same re- 

 agent ; and not only are the sporidia themselves thus affected, but 

 the fluid surrounding them is tinged of an intense purple colour for 

 some distance round the mass of sporidia. This latter colouring is 

 doubtless produced by the effect of the iodine upon a viscid matter 

 which surrounds the sporidia, and which may either originate in the 

 disintegration of the asci, or may be an independent secretion. 

 There can be little doubt, I think, that this viscid matter is starch 

 in a state of solution. It might be taken for dextrine, but that it 

 differs from that substance in assuming a purple colour under iodine. 



The sporidia, although coloured by iodine in the same manner as 

 starch-granules*, do not exhibit any cross when viewed by polarized 

 light. The small size of the Fungi precludes the possibility of pro- 

 curing a sufficient quantity of the viscid matter to test its effect upon 

 the plane of polarization. 



I find the sporidia unaffected by boiling water or even by long 

 soaking in sulphuric acid, in which respect they differ from starch- 

 granules. The purple colour, however (as is the case with starch), 

 disappears under the action of heat or of alcohol. 



I have named the plant Amylocarpus encephaloides, for reasons 

 sufficiently obvious from the above description. Its systematic 

 position is certainly with the Tuberacei, but it has no near allies. 

 The only plant resembling it in structure is Endogone, but it is 

 doubtful whether the vesicles of Endogone be spores or asci. If the 

 latter, the affinity with Endogone would be close. 



In conclusion I may mention, that in a very late number of the 

 'Annales des Sciences Naturelles' (4 serie, vol. vi. p. 318), which 

 has reached me since my first observations on the above fungus, 

 M. Tulasne remarks, that in several species of Erysiphe the tips of 



* The blue colour does not extend to the nucleus of the sporidia, which is yellow 

 under the iodine. 



