July 12, 1895.] 



SCIENCE. 



49 



afford considerable assistance to many 

 workers. 



The method pursued has been to take np 

 literary items in succession, be it a paper, 

 a volume or a series of volumes (for a 

 plentiful supply of which I am indebted to 

 many of your cotintrymen), to thoroughly 

 analyze the contents and to place the data 

 under their approj)riate headings, care being- 

 taken to eliminate all useless repetition. 

 As the subject-matter is divided up into a 

 very large number of headings, the result is 

 the focalization of the data in a systematic 

 sequence, so as to bring into close contiguity 

 the facts bearing on the headings which 

 were originally widely scattered in scientific 

 literature. 



The generical idea is simple enough, but 

 the practical realisation of it is sometimes 

 attended by many difficulties, and involves 

 a great multiplicity of details which can 

 not be described in the limits of a letter ; 

 but some notion may be formed of the scope 

 and extent of what has been done, if a sum- 

 mary is given of the matter already col- 

 lected under the heading ' Animalia : Gen- 

 eral.' 



The Bibliography arranged chronologically 

 by years and alphabetically by authors' 

 names subordinate to the year, at present 

 numbers between 30,000 and 40,000 titles 

 on about 5,000 slips. General; for notes of the 

 most general kind, or of an indefinite 

 character; this covers about 50 slips. De- 

 scriptive; about 30 slips. Classification; 

 about 100 slips, arranged chronologically 

 by years, a remark which applies to all 

 headings. Affinities; about 70 slips. Char- 

 acters ; about 200 slips; arranged by groups 

 (Class, order, etc.) Organic grade; about 

 8,600 slips. This is an attempt to arrange 

 all groups according to their apparent grade 

 on an organic scale, in which the lowest 

 animal is considered to be 1, and the high- 

 est 1,000,000. I believe there is a certain 

 amount of novelty in the idea of numeri- 



cally externatiug organic grade, and there- 

 fore I ventvire to make an extract from the 

 slip which refers to the grade range 55,001- 

 56,000. This is considered to be the high- 

 est limit of the sub-kingdom Protozoa. 

 The class Infusoria and the order Ciliati ex- 

 tend through it and termimate with it. 

 The following families are comprised in it: 



Oxytrichina, 55,001-55,100. 

 Urocentrina, 55,101-55,550. 

 Vorticellina, 55,551-56,000. 

 The following genera are comprised in it: 

 Stylochteta, 55,001-55,033. 

 Oxytricha, 55,034-55,100. 

 Urocentron, 55,200-.55,300. 

 Trichodinopsis, 55,551-55,584. 

 Spirochona, 55,585-55,618. 

 Trichodina, 55,619-55,642. 

 Lagenophrys, 55,643-55,676. 

 Vaginicola, 55,677-55,710. 

 Cothurnia. 55,711-55,744. 

 Ophrydium, 55,745-55,789. 

 G-erda, 55,790-55,824. 

 Scyphidia, 55,825-55,859. 

 Epistylis, 55,860-55-894. 

 Zoothamnium, 55,895-55,929. 

 Carchesium, 55,930-55,964. 

 Verticella, 55,965-56,000. 



It is not supposed for one moment that 

 these figures have any claim to strict scien- 

 tific accuracy. In this resi^ect they are co- 

 equal in value with the classification on 

 which they are based ; their special advan- 

 tage is that they enable a person to give 

 definiteness to his views as to the position 

 of any form, and hence afford a ready 

 means of comparing any number of diiferent 

 views. For instance, if RoUeston's classifi- 

 cation were adopted, the apparent place of 

 Verticella would be at about 142,800. This 

 not only shows a difiPerence of opinion, but 

 also the extent of it ; this definiteness is. 

 calculated to be of great advantage in car- 

 rying on discussion. 



Systemic : general ; about 500 slips. 



