AT THE MICROSCOPE. 35 



take the opportunity of recommending that those who are interested 

 in this subject, and have friends in the West Indies, should en- 

 deavour to prevail upon them to collect the smaller sea-weeds, 

 especially such as are cast ashore in quiet bays and creeks. It 

 should be explained to them that the object is not the sea-weeds 

 themselves, but the diatoms to be obtained from them, and that 

 those sea-weeds are to be preferred, which are covered with para- 

 sites, and entangled with zoophytes, forming what the mere col- 

 lector of algge would call unsightly tufts. They must on no account 

 be washed, but dried in the rough, just as picked up, and then 

 packed in course paper. Small parcels of this kind (a few ounces 

 in weight), from the coasts of the different islands (and from dif- 

 ferent localities of the same island), could not fail to produce 

 objects of the highest interest to diatomists." It should have been 

 stated in the present instance whether the gathering was pure, or 

 if not, what were the associated forms ? 



Hydrodictyon on TJtriculatum (Plate 3, Fig. 2) appears to 

 have been dried before mounting, whereby the remarkable character 

 of the endochrome is entirely lost. It should have been mounted 

 in a cell with Hantsch's fluid, without crushing, or no more than is 

 absolutely necessary. In Johann Nave's " Collector's Handy- 

 Book " it is specially mentioned as one of those puzzling forms, at 

 one time abundant, at another entirely vanished from the spot, 

 without any apparent reason. " It is quite astonishing in what 

 abundance this species will suddenly fill some pond or ditch, at 

 times almost obstructing the flow of water, only to disappear again 

 without leaving a trace behind. So that if a person is anxious to 

 gather a large number of specimens (for the sake, say, of making 

 exchanges), he must be careful to do so w^hile he has the oppor- 

 tunity, and not leave them to a future period, under the idea that 

 they will await his convenience, for he is likely enough in that case 

 to deceive himself, and, on returning to the piece of water, to find 

 only emptiness where the year before there was superfluity. It is 

 far better to secure the requisite number of examples on first 

 coming across the species ; indeed, if necessary, the whole stock 

 may be taken, as there is little likelihood of extirpating any kind 

 of algae." — (Spicer's Translation, p. 4.) 



Coleosporium tussilaginis (Plate 3, Fig. 3) is the name of 

 the fungus on Coltsfoot leaf. Where the latter plant occurs, its 

 special fungal parasite is generally to be found abundantly at 

 this time of the year (July) by turning up the leaves. It does 

 not make a satisfactory mounting when just dried on the leaf 

 (both always losing colour and assuming a dull, dead look). 

 Thin sections should be made with a razor, by laying a por- 



