146 ON THE COLLECTION OF DIATOMACEiE. 



to those of Reinicke's and Gerstenberger's, a poor gathering may 

 ultimately become a very rich one. 



Another mode of collection is by skimming the surface of the 

 sea with a very fine muslin or calico net, having a wide-mouthed 

 bottle tied to an opening in the end, and towed at the stern of a 

 boat. By this means that species of Rhizosolejiia, which bears his 

 name, was found in dense masses by Mr. Shrubsole, whilst on a 

 marine excursion off the Isle of Sheppy ; and other beautiful 

 forms have been similarly discovered by diligent searchers. 



The material brought up by the sounding-line often furnishes 

 subjects for study, more especially the Diatomacese, Foraminifera, 

 and Polycystina. The dredging operations of H. M.Ss. " Challenger" 

 and "Porcupine" rendered immense service in this particular, and 

 I think the readers of our journal would not find it a difficult task 

 to imitate their proceedings on a smaller scale during the ensuing 

 summer. Some four or five pieces of rope-yarn, with the ends 

 unravelled, attached to a short iron bar, and this in turn fastened 

 to a line of sufficient length and strength, will furnish a dredge of 

 much the same character as that employed by the naturalists of 

 H.M.S. "Porcupine." When dragged over the bottom of the sea 

 the rope-yarn becomes filled with objects of interest; and on 

 carefully washing will yield a rich harvest as a reward for the 

 labour expended. 



Enough, however, has been said on the collection of the 

 Diatomacese ; and I would merely add, in closing the first part of 

 my subject, that whilst general instructions are useful, it is not 

 advisable implicitly to follow an arbitrary rule as to the habitat of 

 any distinct species, remembering after all that — experientia docet. 



