Photographing Objects of N'at. History ivithout a Camera. 27 



taken, when of course the lights and shades are as in nature, 

 and the delicate details of venation, etc., if the exposure has 

 been suitable, are beautifull}^ rendered with a roundness and 

 solidity almost incredible. 



Following out this idea I have experimented with seaweeds, 

 zooph3'tes, mosses, ferns, etc. Many of the li3'droids, such as 

 Sertularia, Pluimdaria, and their allies, make excellent slides, 

 the first or negative slide showing the object as brilliantly 

 lighted on a dark ground, there being little or no detail in the 

 interior, and the outline being sharp and crisp. The folia- 

 ceous Fliist7'£E are also suitable, but care must be taken against 

 overlap, which will completely destroy all internal structure. 

 Seaweeds are somewhat more difficult to deal with, as they 

 require in many cases to be set out in water on the clear glass, 

 and then carefully lifted out, and the superfluous water blotted 

 off, before the sensitive plate is applied. When the species is 

 comparativel}^ strong, such as Plocaviium, this is easily done, but 

 in the more delicate forms, like Ptilota, the ramuli run together 

 the moment the water is removed. In this case I have used 

 the plate entirel}^ wetted, with fair success, the only drawback 

 being large air bubbles, which somewhat disfigure the slides. 

 Dried seaweeds are frequently very opaque and most of the 

 detail in the stems has disappeared, but Delesserias and other flat 

 species can be readily photographed diy. Wherever there is 

 detail in the interior, it is better to print a slide from the nega- 

 tive plate, as then lights and shades are not inverted. 



The exposure must of course be learnt by experience, but 

 it may be noted that the red seaweeds, when wet, transmit 

 actinic light freeh^ and so require but short exposure, especially 

 to magnesium. A similar remark is true of such ferns as 

 Trichomanes (Killarne}'^ fern) and Hymenophyllum, and other 

 ferns require of course more, being more opaque. 



There is one direction in which this method of photography 

 might, I think, prove useful, though it is travelling a little out 

 of the title of this note. I notice that Messrs. Newton & Co., of 

 London, advertise a series of lantern slides of grasses, '* made 

 from accurate drawings" for popular educational purposes. 

 Would it not be feasible to make direct photographs in the man- 

 ner above described of the whole^ plant on plates sufficiently 

 large, and from these in the camera make reductions, just as 

 slides are now made from photographic views of all sizes. Such 

 would, of necessity, be more faithful than any drawing could 

 possibly be, while structural details could be brought out in a 

 way that photographing direct in the camera could not pro- 

 duce. 



Whether such photographs of natural objects would be of 

 much value to discriminate species, is I think, doubtful, but 

 it seems to me that they might be ver>' useful in man}- ways for 

 class purposes, especiall}- now that the optical lantern is be- 

 coming so valuable an adjunct in teaching. 



B 



