224 



THAXTER. MONOGRAPH OF THE LABOULBENIACE^E. 



this determinate character is absolute, as a rule, in the more highly specialized portions of the thallus, like 

 the perithecia and compound antheridia. In considering the variations of the receptacle, it is thus con- 

 venient to distinguish in a general way, those forms which are determinate, as in Sticjmatomyces, < 'era- 

 tomyces etc., from those in which, as a result of secondary cell divisions, whether terminal or intercalary, 

 the cell-number becomes more or less variable, as in Ecteinomyces, Dichomyces etc. In the second of these 

 types, two categories may be further distinguished; namely those in which the indeterminate character 

 results from an intercalary division of the main axis, a condition well illustrated by Dimeromyces yin- 

 natus, Plate XXIX, fig. 16, and secondly those in which the secondary production of cells is due to the 

 development of branches, or secondary axes, such as occur in Kainomyces, Monoicomyces, Dimorphomyces, 

 Dichomyces and other genera, usurping the function of the primary receptacle by giving rise to perithecia, 

 or antheridia, or both. 



It is thus convenient to distinguish types which possess a primary receptacle, only, corresponding to 

 the original axis of the basal spore-segment, and immediately concerned in the production of procarpic 

 branches; from those in which the primary receptacle, though present, is sterile; the production of 

 sexual organs being relegated to secondary axes which branch laterally from it and may be distinguished 

 as secondary receptacles. Among genera of the first category, in which the primary receptacle is determi- 

 nate and fertile, those types in which the latter consist of two superposed cells are the most common, and 

 of these the simplest condition is illustrated by Amorphomyces. In neither sex of this dioecious genus is 

 it associated with sterile cells or appendages; the type being quite anomalous in possessing a continuous 

 spore, from which the procarp in the female, as well as the antheridium in the male, develop terminally. 

 In no other genus is the axis of the procarp continuous with that of the primary receptacle, although, as 

 in Kainomyces, it may sometimes bear this relation to its branches. This condition is directly depend- 

 ent on the fact that in all other genera, even in the very closely related Dioicomyccs, the spore is once- 

 septate, the distal segment becoming a "primary appendage," which is either sterile, or is concerned in 

 the production of antheridia. This condition is illustrated on the one hand by Dioicomyces, the species 

 of which possess a two-celled receptacle surmounted by a sterile portion corresponding to the distal 

 spore-segment and bearing the procarp laterally; and on the other by such genera as Eucantharomyces, 

 Stigmatomyces, Corcthromyces and many others, in which the terminal spore-segment produces an antheri- 

 dial appendage of varying complexity. 



Instances in which the primary receptacle is two-celled and sterile, are found in both the monoecious 

 and dioecious genera, and by far the most remarkable illustration of this condition is seen in Herpomyccs, 

 in which the perithecia are borne on secondary receptacles that are more clearly differentiated than in any 

 other instance. In the female individuals of the species of this genus, Plates XXXIX-XLI, a variable 

 number of branches may thus arise, which originating as simple cylindrical filaments, soon become cellu- 

 lar, forming secondary receptacles which creep more or less extensively, or are variably multiplied in 

 different species by branching; perforating the host-integument, as has been above described, by means 

 of thread-like rhizoids which render these structures independent of the original foot as far as their food- 

 supply is concerned. This peculiar condition is in general confined to the female individuals, although 

 in H. Ectobiw it is equally prominent in the male. Branches which become adherent to the host have 

 been described in no other instance, although they are known to the writer in one other peculiar dioecious 

 genus as yet undescribed, but it is not difficult to imagine that such a condition might either have origi- 



