398 SUMMARY OF CURKENT RESEARCHES RELATING TO 



that of Phycomyces ; the spores are coloured by iodine a mahogany 

 brown. In M. stolonifer it is especially difficult to detect, because of 

 the extreme sensibility of the protoplasm to coagulate with iodine ; it 

 permeates the jirotoplasm of the stolons, fertile filaments, and young 

 sporangia. It accumulates locally in opalescent masses, similarly to 

 the epiplasm of Peziza and Ascoholus ; the cell- walls of the fertile 

 filaments are coloured a dirty rose by iodine. 



M. Errera also records the occurrence of glycogen in Piloholus 

 crystallinus, and in other species of the same genus ; and in Chceto- 

 cladium Jonesii, Piptocephalis Freseniana, and Syncephalis nodosa and 

 minima. 



As a control experiment, glycogen was extracted from the Phyco- 

 myces, by a method. Avhich is described in detail, and recognized by the 

 ordinary chemical tests. 



Heteroecism of the Uredines. * — C. B. Plowright gives his ex- 

 periments on the connection of certain fecidial and teleutosporic 

 forms of Uredinece. His experiments were started in 1881 with 

 cultures of the spores of ^cidium Berheridis on wheat ; but as Uredo 

 linearis, which is the uredo-stage of Puccinia graminis, appeared on 

 the control plants as well as on those on which the fecidial spores 

 were sown, he was not able to confirm the connection between ^cidiiim. 

 Berheridis and Puccinia graminis which is accepted by Continental 

 botanists. In 1882 he repeated his experiments on a larger scale, 

 and with a more satisfactory result. In the case of Puccinia graminis, 

 the mildew of wheat, he not only succeeded in producing Uredo linearis 

 on wheat by sowing the ascidial spores, the control plants remaining 

 healthy ; but he reversed the experiment, and produced Mcidium 

 Berheridis by sowing the Puccinia spores. He also powed the spores 

 of Podisoma Sabince and P. Juniperi on pear and CratcBgus seedlings, 

 and j)roduced Boestelia cancellata and B. lacerata respectively. The 

 sj^ores of Gymnosporangium Juniperi, sent from a distance of several 

 hundred miles, when sown on Sorhus Aucuparia, were followed by a 

 growth of Boestelia cornuta, a species never before seen by Plowright 

 in Norfolk, where the experiment was made. He also experimented 

 with other sjiecies of Puccinia, Peridermium, and Uromyces, and suc- 

 ceeded in confirming the views of Continental writers as to their 

 secondary forms, in one instance producing a Puccinia not before 

 known in Britain, and in the case of Uromyces Junci, showing the 

 relation to JEcidium zonale which was suspected by Fuckel. 



No writer since De Bary has shown more successful results in this 

 difficult subject, and Mr. Plowright deserves great praise for his 

 careful experiments. Except in one series of cultures, the fully 

 developed secidial form was obtained, and not the spermogonia alone, 

 as had been the case with some other investigators. Although most 

 of the experiments were rather in confirmation of those of other 

 botanists, in a very important respect he has added to our previous 

 knowledge. One great difficulty in the way of accepting the connec- 

 tion between JEcidium Berheridis and Puccinia graminis has been that 



* Grevillea, xi. (1882) pp. .52-7- See Amer. Journ. Sci., xxv. (1883) pp. 314-6. 



