Further Contributions to the Cytology of the Ascomycetes

With Plates XXVI and XXVII, and a Figure in the Text.R ECENT investigations by one of us ( 13) have shown that in Humaria rutilans a meiotic reduction, involving transverse fission of the heterotype chromosomes, takes place in the first two divisions in the ascus, and further, that it is followed, in the third mitosis, by a second, or brachymeiotic reduction of a simpler type.These processes accord with the observations of Harper ( 19) on Phyllactinia but have not been described in other forms; the present researches were undertaken as a first step towards ascertaining whether they are of general occurrence among Ascomycetes.We have found, in the two species with which this paper deals, intermediate stages between the early union of the chromosomes in Phyllactinia and their independence during the stages which precede reduction in Humaria ruiilans and in higher plants and animals.Material was obtained in Windsor Park during the autumns of 1906 and 1907, and was fixed in the field in various strengths of Flemming's fluid.Before staining, many of the slides were immersed for three or four hours in a solution of pepsin 1 and 0-2 per cent, hydrochloric acid at a temperature of 38° C.This treatment facilitated the study of the chromatin.Sections were cut 5-10 ft in thickness and were stained with Heidenhain's iron-haematoxylin or with Flemming's triple stain. OTIDEA AURANTIA.This species has a large, orange apothecium which increases considerably in size after the asci have begun to form.In the early stages of development a large cell with scanty contents is present, and represents,