HARDWICKE'S SCIENCE-GOSSIP. 



269 



Pythium, as well as the Peronospora, is found. 

 (2) The same cells in the Saprolegnieas will alter- 

 nately produce, under the same (or different) con- 

 ditions, zoospores or resting spores ; therefore, if 

 zoospores are produced in Mr. Kenny's oogonia in 

 water, it is reasonable to assume that under dif- 

 ferent conditions resting spores would be formedjby 

 similar cells. I have, from the first, believed the 

 Saprolegnia condition of the fungus to be widely 

 diffused, and when in that state it quite possibly 

 grows on diverse plants and substances in watery 

 places, as was explained by me. The Saprolegnia 

 is the caterpillar condition (belonging to the water, 

 like the larva of the dragon-fly), the Peronospora 

 somewhat analogous with the perfect butterfly, and 

 the resting spore with the dormant chrysalis. 



5. I find by experiment, when badly diseased 

 haulm, fruit, and tuber are partly submerged for 

 from one to four days, the Peronospora changes its 

 character, and produces the Pythium or Saprolegnia- 

 like growth on the submerged parts. On examina- 

 tion of the plants, this may be easily overlooked, as 

 the Saprolegnia commonly frees itself and floats on 

 the surface of the water, and must be carefully 

 taken off (invisible as it is) with a camel-hair pencil. 

 If the oogonia now produce zoospores in the water, 

 as in Pythium, which is possible and even probable, 

 it in no way invalidates my views, or makes the 

 connection less probable between Pythium and 

 Peronospora. 



6. The aerial spores of the Peronospora never be- 

 come globular in water, whilst the oogonia and 

 antheridia are always so. 



7. A superabundance of water excites the growth 

 of the mycelium, but it retards the proper produc- 

 tion of the resting spore, just as a superabundance 

 of water in most plants makes leaves and retards 

 flowers. 



8. In my calendar of the weather I find we had 

 here only five wet days from May 7 to June 10 (no 

 wet between May 8 and 20), and it was during this 

 dry weather that the potato fungus this year lived 

 inside, and at the entire expense of the plant, and 

 there perfected its resting spores. With the 

 twenty-two wet days after June 10 the Perono- 

 spora put on its usual shape, and came to the sur- 

 face. 



9. I have got my most abundant materials from 

 the tuber when soft and almost transparent, like 

 painters' size. In this state the starch is utterly 

 destroyed, and, what is most curious, there is no 

 offensive smell. The tuber frequently decomposes 

 with a horrible fetor, and turns whitish inside ; the 

 starch is then present, and more or less injured, and 

 very little can be seen of the fungus. 



10. The season is too far advanced, and the fun- 

 gus has already caused too much destruction to 

 think of grappling with it this season, but when it 

 is remembered how the vine, the corn, and holly- 



hock parasites have been restrained, it certainly 

 doe3 not seem impossible that means may be found, 

 to mitigate the damage done every year by the 

 potato murrain. 



ON SETTING AND PRESERVING 

 HYMENOPTERA. 



TV/l'Y attention having been attracted by an article 

 -*-'-*■ under the above heading in your October 

 number, I trust I may be allowed to make a few 

 suggestions thereon. In the first place, to my mind 

 the method pursued by Mr. Bridgman in killing his 

 specimens is far too complicated. He first stupefies 

 the insects with cyanide of potassium, then pill- 

 boxes them. When they have revived, he doses 

 them with chloroform ; and then, lest they should 

 survive this treatment, he subjects them for the 

 space of three hours to an elaborate sulphur-bath, 

 whence they are transferred " into a damp box for 

 twelve or more hours." Cyanide of potassium has 

 two objections. It is apt to turn the colour of some 

 insects. Sulphur has the same objection ; and the 

 vapour it evolves is unpleasant to inhale, causing 

 headache and nausea with some people. Chloroform 

 is expensive, difficult to keep, on account of its rapid 

 evaporation, and dangerous. The plan I have found 

 most efficient, and I believe there are few I have not 

 tried, is as follows : — 



On a fine, dry day collect some couple of dozen 

 or so of the common green laurel-leaves: be sure 

 they are perfectly free from all external moisture, 

 or they will be likely to turn mouldy. Then procure 

 a wide-mouthed bottle ; cut the leaves into small 

 pieces, aud fill to within two inches of the mouth. 

 Cut also some paper discs, the size of the bottle, 

 and press them flat on the top of the leaves ; two 

 will be sufficient. In a few days the leaves will 

 turn brown, when it is ready for use. 



This is my Store-bottle. 

 ' For the sum of one shilling you can purchase at 

 any entomological " naturalist's " one of the zinc 

 pocket collecting-boxes Mr. Greene recommends. 

 Fill the chamber beneath the perforated bottom 

 with equal parts of camphor and ammonia, and then 

 you will have one of the most powerful killing-boxes 

 extant. When out collecting, it is as well to have 

 two of these boxes in your pocket ; and when you 

 have some fifteen or twenty specimens in one, use the 

 other for a time. Then you can empty the contents 

 of the first one into a pill-box, and it is ready for 

 use again. There is one disadvantage in connec- 

 tion with the box; viz., the inside surface of the 

 overlapping part of the lid requires oiling now and 

 then, to prevent it sticking ; and, if not kept dry, 

 the ammonia is apt to deliquesce. I generally 

 renew mine once a month, soaking the box in hot 

 water. 



