16 



HARDWICKE'S SCIENCE-GOSSIP. 



[Jan. 1, 1867. 



that never knew each other should have so many 

 acquaintances ; and, look here,' he says to one of 

 the police, 'there's something quare about this; 

 just read that word.' 'Well,' says the policeman, 

 ' I am not a great reader, read it yourself.' And 

 he began to spell — ' di-i-a-t-o-&c.' Observing his 

 perplexity, I told him that the word was ' Diatoma- 

 ceous earth,' and if he required to know further, he 

 must refer to ' Pritchard's Infusoria ' or ' Smith's 

 Diatomaceae.' He professed to know all that, but 

 still he was certain 'there was something about it 

 that required to be explained ! ' " Suffice it to say 

 that on the return of the head-constable, his ex- 

 anination of the papers, &c, after some altercation, 

 to the great annoyance and chagrin of the " harbour- 

 constable," Mr. Gray obtained his liberty again 

 between 10 and 11 o'clock at night. We regret 

 that our space would not allow us to reprint Mr. 

 Gray's letter in full. It is a most amusing episode, 

 as good as a farce to any but our unfortunate corre- 

 spondent. 



WHEAT MILDEW (Puccinia graminis). 



rTlHE wheat mildew is but too well known in .its 

 -*- external appearances to all who are interested 

 in agriculture, to need much description, and even 

 amongst townsmen there are but few who have not 

 heard of it, many that on account of its reputation 

 have made acquaintance with its uninviting exterior. 



Fig. 9- 



Of its internal and microscopical character very few 

 of those who know it as a pest have any experience, 

 and it is with a view to its better acquaintance that 

 we have selected it for illustration. Early in the 

 year and whilst the plant is still green the leaves of 

 wheat and grass become more or less covered with 

 a bright rust-coloured or orange powder, which 

 bursts through the cuticle and disperses itself over 

 the surface of the plant. This is what has been 

 called the " rust," and is undoubtedly a stage or 

 condition of the mildew, and if examined micro- 



scopically in the autumn the globose or elliptical 

 spores of the rust (fig. d) will be found in all stages 

 intermediate between the simple form and the elon- 

 gated septate spores of the " mildew " (fig. c). The 

 mature mildew occurs on the yellow straw, and 

 fading leaves at harvest time, in elongated dark- 

 brown, almost black sori, or compact tufts, bursting 

 through the cuticle (fig. a) ; and if a portion is 

 removed with the point of a penknife and placed 

 with a drop of water on a slide the tufts will be 

 seen to be composed (fig. b) of a mass of stalked 

 spores, each divided transversely by a medial wall or 

 partition, dividing each spore into two nearly equal 

 parts, of which the upper is more deeply coloured 

 than the lower, and blunt or obtuse at the apex. 



It was long believed in agricultural districts that 

 wheat grown in the neighbourhood of Berberry 

 bushes was sure to be mildewed, and that there was 

 some mysterious connection between the Berberry 

 and the mildew. In consequence of this belief the 

 Berberry was carefully extirpated from the neigh- 

 bourhood of cornfields. Scarcely more than twelve 

 months ago Dr. De Bary announced that as the 

 result of careful experiments he had come to the 

 conclusion that the parasite (JEcidiurn) of the Ber- 

 berry was only another condition of the mildew of 

 the wheat. Although his observations require con- 

 firmation before they are accepted as incontrovertible 

 fact, there is every reason to believe that there is a 

 mysterious link which unites the two parasites. 

 For many years mycologists have strenuously opposed 

 the popular belief as a vulgar error, and in 1S13 an 

 eminent authority in the pages of the " Gardener's 

 Chronicle " (p. 694) observed, " we should as soon 

 soon believe that a hen's egg would be hatched into 

 toads as that the seed of an JEcidium would produce 

 Uredo or Puccinia." Twenty-one years after this 

 and there is every probability of its becoming an 

 admitted fact that Uredo (or Trichobasis) and 

 JEcidium are the same plants as Puccinia indifferent 

 conditions of a kind of " alternation of generations." 



M. C. C. 



ZOOLOGY. 



Spidek Poison. — I have read with some interest 

 the discussion which has appeared from time to 

 time in the pages of Science Gossip regarding the 

 poisonous property of the spider. The little article 

 in a recent number has, I should presume, settled 

 tYivfact that the .insect is endowed with a poison 

 apparatus. I have been curious to observe if any 

 of your readers' experience on this point has been 

 similar to my own, and as no one has as yet quoted 

 personal experience, I now venture to state mine. 

 One summer morning, feeling a smart degree of 

 irritation about the middle of the forearm, instead 

 of rubbing the part as one instinctively does, I 

 cautiously turned up my shirt-sleeve a little, when, 



