1890.] NATURAL SCIENCES OF PHILADELPHIA. 37 



triangular in section in the upper two-thirds of their length, instead 

 of being cylindrical as usual. 



This irregular shape was due to the anomalous position of the col- 

 umella which was lateral and not central, running from the base of 

 the sporangium nearl}'- to the end, in a spiral of about two and one- 

 half turns, appressed and closely attached to the inner face of the 

 sporangium wall. 



The internal capillitium, usually composed of radial threads run- 

 ning from the central columella to the peripheral network was want- 

 ing ; but in place of it, a few delicate threads bound the columella, 

 at short intervals to the periphery, and then ramified for a little dis- 

 tance upon the latter. 



The sporangium wall or periphery was most remarkable, being, 

 in efiect, a rigid sheath of plasmodic matter, perforated by circular 

 and oval openings, instead of the peripheral network of threads par- 

 allel to the axis of the sporangium, which is characteristic of typical 

 Stemonitis. At intervals, on the surface of this plasmodic sheath, 

 knots were developed from which short threads branched in all di- 

 rections, sometimes connecting with those binding the columella but 

 generally blending with the substance of the sheath. 



As the season was advanced no other specimens were found in that 

 year, but in the following year, three crops of Stemonitis were suc- 

 cessively developed at intervals of about one month on the same area 

 of log surface which had been carefully marked and noted. Bv a 

 warrantable inference these growths were developed from the spores, 

 or part of the same plasmodium as the specimens of the previous 

 year. Each crop bore the main variant characters of the original 

 specimens, but approached successively nearer the true Stemonitis 

 type. 



The last found growth differed but slightly from Stemonitis Bau- 

 erlinii Mass., yet, as it presented all its diagnostic characters, the 

 whole series could logically be referred to that species. 



These and all similar variations in the sporangia of the myxomy- 

 cetes, are caused by the irregular or unusual differentiation of the 

 formative plasmodium during development. In the present case, the 

 sporangium wall gained an increased amount of plasmodic matter at 

 the expense of the central capillitium. 



Whether this change was abrupt, or the result of several genera- 

 tions leading to it, could not be known, but the observations which 

 were made, though lacking some of the essentials of scientific exact- 

 ness, seemed to show- a very interesting example of the reversion of 

 an extremely variant form to its original type. 



The speaker believed that this abnormal form would again be de- 

 veloped and found, and he desired, therefore, to place it on record 

 as Stemonitis Bauerlinii Mass. f fenestrata. He acknowledged his 

 indebtedness to the courtesy of Mr. George ^Nlassee, the author of the 

 species, for an authentic specimen of Stemonitis Bauerlinii. 



