28 



PRINCIPLES OF PLANT-TERATOLOGY. 



the Agaricus fumicola mentioned by De Seynes, on 

 which there was a central, inverted and stipeless 

 cap which he says could not have been formed by 

 invagination, as there is no sign of any notching of 

 the margin of the primary cap ; so he ascribes it to 

 prolification. Here also probably belong the cases 

 observed by Ferry of small, inverted caps, without 

 stipes, on Clitocybe nebularis, which arose at first 

 sub-epidermally, and which he states were due to 

 smaller individuals being carried up by, and engulfed 

 in the tissues of, the larger one. On the other hand, 

 there may be cases which are intermediate between 

 the two sets of phenomena. Hymenial portions might 

 have become invaginated on to the upper surface at a 

 young stage of the primary cap, and later, by the 

 subsequent fusion across of the marginal lobes, have 

 become isolated, appearing, therefore, in the mature 

 stage of the primary cap as having congenitally arisen 

 in that position. It is just possible that the inverted 

 cap of Tricholoma grammojp odium shown in PI. I, 

 fig. 1, may have arisen in this way, as the cap is 

 inclined to one side, which may be that on which the 

 invagination occurred ; there was, however, no sign 

 in the specimen of any fusion of lobes on that side, 

 the margin being perfectly even and continuous, so 

 that this also may be regarded as a case similar to 

 those just cited of De Seynes and Fries. 



In fig. 4 is seen, in Clitocybe clavijpes, a good case 

 of imperfectly -formed inverted caps due to invagina- 

 tion at three points of the circumference of the 

 primary cap, for the traces of their origin are obvious. 

 The secondary ones seem to have ordinary gills. In 

 the case of Tricholoma sordida, shown in PI. I, 

 fig. 5, we see an early stage in the formation of an 

 inverted cap by invagination stereotyped and fixed 

 for us in the mature structure ; it will be noticed that 

 the most invaginated portion, viz. that nearest the 

 centre of the cap, has a foveolate hymenial tissue, as 

 is also the case with the tiny abstricted portion still 



