i8 TEXT-BOOK OF FUNGI 



peculiar properties were not due to some foreign deposits 

 in the cell-wall, or to some other causes. 



It has been shown by Wisselingh that as a rule the cell- 

 walls do not consist of a special form of cellulose, or 

 fungus-cellulose, but contain chitin, similar to that so 

 frequently met with in the animal kingdom. The test for 

 this substance is as follows. Hyphae are put into a sealed 

 tube in 80 per cent, of hydrate of potash, and heated for 

 two hours to 1 60 C., and afterwards placed in 90 per cent, 

 alcohol. On the addition of a solution of iodine 'and dilute 

 sulphuric acid the characteristic plum-pink colour of chitin 

 is seen. 



Pits are frequently present in the cell-wall. In the 

 capillitium threads of many species of Lycoperdon^ the 

 lateral wall shows minute pits irregularly scattered. In the 

 case of superposed cells forming long strands, as in the 

 stipes of Agarics, the conidiophores of various moulds, 

 etc., the transverse walls are perforated by a minute central 

 pit, thus admitting of continuity of protoplasm, as in the 

 red seaweeds or Florideae. Poirault has stated that con- 

 tinuity of protoplasm is also present in lichens, the proto- 

 plasm passing through a minute pit in the centre of the 

 wall. Continuity of protoplasm is, however, most evident 

 in the Laboulbeniaceae. 



The most highly differentiated pits that I have observed 

 occurred in the blood-red sclerotium of an orange-coloured 

 Hyphomycete called Rhinotrichum aureum. These pits 

 closely resemble in general appearance and structure the 

 bordered pits met with in the Coniferae. 



The protoplasm usually occupies the whole of the cavity 

 in young cells, and generally presents a granular appear- 

 ance. In full-grown cells it becomes vacuolate, and finally 



