326 Blackman. — On the Fertilization, A Iter nation of 
forms with special attention to aecidium-development and the character 
of the spermatia. With this object there were chosen as likely to be 
favourable objects, Phragmidium violaceum , Wint. 1 , a common autoecious 
^-form found on the various forms of Ruhns fruticosus , and Gymno- 
sporanginm clavariaeforme , Rees, a heteroecious form with the spermogonial 
and aecidial stage on various species of Crataegus , and the teleuto- 
spore stage (uredospores are wanting) with a perennial mycelium on 
Juniperus communis , L. Material of the last-named form was obtained 
in abundance from the neighbourhood of Crockham Hill, Kent, where the 
infected Hawthorn and J uniper are often to be found in close proximity. 
A careful study of these forms, especially of Phrag. violaceum , shows 
very clearly that a definite fertilization is to be observed in the aecidium, 
that the Uredineae show a well-marked alternation of sexual and asexual 
generations, and that the fusion in the teleutospore, the nature of which has 
been so much disputed, is relatively of unimportance, being a mere 
preliminary to reduction. 
Methods. 
The material used was fixed chiefly with either Flemming’s fluid (usually 
the weak formula) or with acetic alcohol which was allowed to act only 
for a short time. All material, except that for the study of teleutospore- 
germination, was fixed in the field, an air-pump being used in the case 
of the non-alcoholic fluids to remove air from the surface of the pieces and 
so facilitate the penetration of the fluid. The material after fixing, washing, 
and dehydrating was preserved in equal parts of alcohol, glycerin, and water. 
For staining, Flemming’s triple stain, Benda’s iron-haematoxylin, and 
brazilin were all found very useful ; for the latter stain it was found 
convenient to use, instead of the ordinary alcoholic iron-alum solution, 
which goes bad very quickly, a solution made by diluting Benda’s 5 Liquor 
ferri ’ with about nine parts of 70 °/ o alcohol. This mixture remains unpre- 
cipitated for many months. 
For the study of teleutospore-germination G. clavariaeforme was found 
very favourable. The masses of teleutospores will retain their power of 
germination in a cool place for over a month. If pieces of the bark with 
the masses attached are placed for a few seconds in water under an air-pump 
so as to get them thoroughly wet, and then in Petri -dishes over damp 
filter-paper at a temperature of 20° C., germination takes place very readily 
and sporidia are formed in less than three hours. Very good results in the 
study of nuclear divisions in the germ-tube were obtained by the use 
1 The characters which distinguish this species from that of Phrag. Rubi, Wint., are very un- 
satisfactory and the two forms should probably be united. The form here investigated is obviously 
the same as that studied by Sapin-Trouffy, which he calls P. Rubi , but as there are usually four cells 
to the teleutospore and only a slight projection at the apex the other name seems preferable. 
