CHAPTER I. — HISTOLOGICAL CHARACTERISTICS. J 



colouring matter or amy lum- grains, nor, as far as is known, any vehicles for colouring 

 matters nor their homologous plasiids (A. Meyer's trophoplasts). 



It would appear that the formation of fatty matters takes the place very generally 

 of the amylogenesis which holds in plants containing chlorophyll; these matters 

 always form a percentage of the dry substance of vegetating Fungi, and may 

 amount with diminution of the proteid substances to 50 per cent, of the material 

 stored up in the resting-states, to 35 per cent, in the fatty sclerotia of plants like 

 Claviceps, and to 50 per cent, in the Moulds (? Penicillium) in the resting or 

 involution-stage, that is, after the close of vegetation. During the time of active 

 vegetation the fatty substances are disseminated in the form of minute drops in 

 the protoplasm of the cells of Fungi, as they are in the cells of other plants, and 

 help to make it look granular or turbid; in the resting states (periods of involution), 

 in which reserve-material is stored up, they may collect into large strongly refringent 

 drops which occupy the largest part of the cell-cavity. Examples of the latter case 

 are the sclerotia of Claviceps, the thallus of Sphaeria Stigma, Fr., S. discreta, Schw., 

 S. eutypa, Fr., Vermicularia minor, old moulds, many spores, &c. &c. 



In many cases the collections of fatty matter are colourless or only faintly 

 coloured, but sometimes they are very highly coloured, if after the analogy of cases 

 which have been carefully and chemically examined we may venture to apply the 

 term fatty substance to bodies, of which we only know with certainty that they agree 

 with fatty aggregates in outward appearance and in the ordinary microchemical 

 reactions. If the bodies in question are really to be regarded as chemically 

 definite fats, it still remains to be decided whether the colours belong to the fats 

 themselves, or are derived from distinct colouring matters which would in that case 

 be attached to the aggregates of fatty matters as their vehicles. With this reservation 

 and pending the requisite strict chemical examination, we may designate as coloured 

 aggregates of fatty substances those microchemically fat-like bodies which produce 

 the characteristic colouring from yellow to brick-red in so many Fungi — Uredineae, 

 Tremellineae, Stereum hirsutum, Sphaerobolus, Pilobolus, many Pezizas as P. aurantia, 

 P. fulgens 1 , and various other kinds. They are found thinly disseminated in the 

 protoplasm of actively vegetating and growing cells, imparting to it a uniform 

 colouring ; after the death of the cells they often run together into larger drops ; 

 in older cells also they sometimes assume this form spontaneously. In the Uredineae, 

 and according to Coemans in species of Pilobolus also, the red colouring matter 

 shows a characteristic reaction, becoming intensely blue when treated with sulphuric 

 acid, then quickly passing into a dirty green and then gradually losing all colour, 

 a reaction which is seen in the similar red colouring matter of many parts of plants 

 which do not belong to the Fungi, and in the red pigment-spots (eye-spots) of 

 some of the lower forms of animal life. This reaction is not found in the other 

 Fungi mentioned above. These facts sufficiently point to a different material 

 composition -of the bodies in question in different cases : some of them were 

 spectroscopically examined by Sorby. 



Van Tieghem discovered crystalloids of albuminoid substance {inucoriii) in 

 the gonidiophores and zygosporophores of most of the Mucorini. J. Klein found 



1 P. fulgens, Fr., was named P. cyanoderma in the first edition of this book. 



