GENERAL INTRODUCTION TO THE ZOOLOGICAL REPORTS. 21 



were screwed to the bulkheads ; and for examiuiug minute surface animals at night, when 

 they were frequently in greatest abundance, the " Bockett " microscope lamp, made by 

 Collins, was found most useful. Three of Hartnach's small-model microscopes with 

 objectives 2, 4, 7, 8, and 10, were in constant use in the work-room, but one of Smith 

 and Beck's binoculars was found more convenient for observing surface animals by 

 reflected light. Several other microscopes by Ross, Zeiss, and other makers were avail- 

 able, and a number of ordinary dissecting microscopes. 



The heat of the Tropics affects unfavourably many of the substances in common use 



FlO. 12.— The Naturalists' Work-room. 



for mounting microscopic preparations ; thus glycerine jelly -nnll scarcely set at all, but 

 remains nearly fluid, and the different varnishes and lacs continue soft and sticky. It 

 is unsafe to pack preparations on edge, and we find small pine wood cases, supplied by 

 Charles Baker, High Holborn, containing each twelve horizontal trays with accommoda- 

 tion for six dozen slides, most suitable for storing. It is difficult to keep instruments, 

 particularly those which are necessarily made of steel, in working order on board a ship ; 

 even with great care, they are so rapidly destroyed or lost. For this reason it is necessar}- 

 to have an almost unlimited supply of those in most frequent use, such as scissors, 



