HARDWICKE'S SCIENCE -GOSSIP. 



203 



juice of horse- dung diluted with water. As I wi s 

 quite in the dark as to the habits of these resting- 

 spores, of course I did not know what to do for the 

 best, or what the result of my experiments would 

 be. I have already described how these resting- 

 spores at first floated on the surface of the water, 

 how they at length deposited themselves in the 

 sediment at the bottom, and how, on opening one 

 of the bottles at the last meeting of botanists at 

 Hereford, the resting-spores were found still intact 

 and apparently alive. Happily for me, nearly all 

 my spores retained their vitality. Mr. Broome, 

 being equally uncertain with myself, trusted to 

 chance, aud chance so far favoured him that all his 

 resting-spores in the slanting saucer of water well 

 retained their life. It might have been (and even 

 was) said that possibly some fungus foreign to the 

 Potato fungus had got into my material ; but if so, 

 it must be regarded as a coincidence in the highest 

 degree extraordinary that Mr. Broome should also 

 get the same new and foreign fungus in his Pero- 

 nospora material,— a body so puzzling in its nature 

 as to be referred to no less than eight different 

 species of fungi. 



All who have studied the habits of the lower 

 fungi know the extreme difficulty of preserving the 

 specimens alive. This difficulty almost amounts to 

 an impossibility. The fungi under study may be 

 present one day and all gone the next ; a few drops 

 of extra moisture or a slight current of dry air is 

 sufficient to destroy or collapse the whole lot. Be- 

 sides this, myriads of other parasitic fungi, and 

 whole tribes of infusoria, commonly make their 

 appearance, and prey upon the material that is 

 desired to be preserved. 



Now one of the most extraordinary facts about 

 the recent Potato investigations in this country is 

 this. These other fungi and infusoria have not to 

 any damaging extent appeared. Since I opened 

 my sealed bottles last April, I have kept the 

 material under a bell-glass, and there has been no 

 offensive odour, and to no appreciable extent have 

 there been any moulds, infusoria, or parasites 

 except Peronospora infestans itself, and the other 

 fungus, which is equally destructive to potatoes, and 

 known under Fusisporium Solani. In investigating 

 the Potato disease, it was almost as important to 

 discover the entire life-history of the Fusisporium 

 as the Peronospora, and fortunately the materials 

 preserved gave a perfect clue to the entire life- 

 history of both. Mr. Broome's material has in the 

 same manner been free from an excessive number 

 of other fungi and infusoria. 



The germination of the resting-spores was 

 awaited with the greatest anxiety, and as 1 never 

 knew from one day to another whether or not these 

 bodies might all collapse and perish, I was under 

 the necessity of dividing the material, and keeping 

 a constant look-out for results under different con- 



d itions. With this object in view, therefore, I kept 

 some of the bodies moist in pure water, others in 

 dduted expressed juice of horse- dung, others in 

 expressed juice of fresh potato-leaves, others upon 

 extremely thin slices of potato and on crushed 

 potato-mash, others in saccharine fluid, others in 

 nitrogen gas, some between pieces of glass kept 

 constantly moist, some upon broken tile (also kept 

 constantly moist), and some upon potato-leaves as 

 they grew upon the living plant. Besides this I 

 have had a quarter of a hundred of slides kept 

 damp, and under examination every day (almost 

 night and day) for the last three months. All these 

 preparations I have kept constantly and uniformly 

 moist under darkened bell-glasses, for darkness in- 

 variably assists the growth of spores of all sorts. 



The first new fact worthy of note is this : many 

 of the resting-spores grew in size during nine 

 months of their rest to twice their original diameter, 

 or about four times their original bulk, and their 

 aspect gradually changed from almost smooth, semi- 

 transparent bladders to brown, more or less rough 

 and warted or echinulate spheres. These latter 

 brown, mature bodies were quite the same in cha- 

 racter with those so sparingly seen last June and 

 July. How they arose last year no one saw, but 

 probably the wet weather of the early summer 

 caused their appearance. It does not follow, 

 because the resting-spores have taken a year to 

 artificially mature with me, that therefore they 

 always take a year to ripen; it is quite possible 

 that, in a state of nature and under different con- 

 ditions, they may mature rapidly. At any rate, two 

 sorts of bodies were seen together last year, trans- 

 parent smooth bodies and rough brown ones. I 

 considered them to be different states of the same 

 resting-spores, and subsequent facts have proved 

 my supposition to be quite correct. 



The top row of illustrations on fig. 113 shows cha- 

 racteristic conditions of the almost mature repro- 

 ductive bodies as drawn in April last. At A is seen 

 the oospore (or resting-spore) within the oogonium 

 (bladder which holds the resting-spore) ; at b may 

 be seen two resting-spores within one oogonium, and 

 at c three resting-spores within one oogonium; 

 whiist at d is shown a double oogonium — two oo- 

 gonia coalesced, and each oogonium containing a 

 resting-spore. 



At the end of April and beginning of May last I 

 began to see the first signs of germination, and at 

 this time many of the oospores proved effete ; the 

 oogonium cracked at e, or became broken into 

 atoms, as at r, discharging a bladder, as at a, which 

 perished in fine dust, as at H. 



As the month of May progressed, many of the 

 resting-spores became dense and dark, with the 

 oospore occupying the whole of the oogonium, &z 

 at I : this condition is different from that of the 

 body A, for in this the resting-spore, being not quite 

 mature, does not yet occupy all the oogonium, but 



