26 THE VARIETIES OF THE HUMAN SPECIES. 



The practical method which I have already adopted, for me and 

 others who wish to make use of it, is that of placing the series of 

 crania in order and in an equal row upon a large table, the first 

 time, if possible, of the same color, intact, that is, without having 

 been sawed to extract the brain, without the lower jaw, and there- 

 fore upon a single plane, each placed upon its base. Difference of 

 color, the line which divides a cranium sawed, an inequality in the 

 table, may alter the positions of the forms or render the discovery 

 of similarities and dififerences more difficult. 



When familiarity with the forms has once been acquired, many 

 of the conditions become superfluous, and then an isolated 

 cranium is classified without the necessity of a comparison, at least 

 in the forms which are common. 



After various and attentive observations and continuous com- 

 parisons, it is necessary to form groups of crania which seem to 

 have common characteristics. Formed in groups, each group must 

 be separately analyzed in every component, in order to recognize 

 common and diverging characteristics; if these last are marked, 

 separate the groups into subgroups, noting the individual differ- 

 ences which must necessarily exist. 



Formed in groups and subgroups, one typical cranium is 

 selected for each group or subgroup, and its likeness is trans- 

 ferred by drawing a free-hand outline, by placing the cranium 

 itself upon paper, or by means of a camera, and finally the volume 

 is reduced, or rather the linear magnitude, to a third or half, mak- 

 ing this reduction equal in all the crania which are designed. 

 Drawing has the very great advantage of revealing the linear 

 curves, which are not immediately observed, and demonstrates 

 characteristic dififerences very easily. In case of doubt concern- 

 ing certain forms which seem similar, it is well to place the pro- 

 files one above another, in order readily to observe similarities and 

 dififerences, whether apparent or real, profound or superficial. 



The following are additional rules : Distinguish the crania which 

 compose the groups according to sex, because sexual dififerences 

 should not impair or alter the types under which the crania are 

 classed, nor should another type be made on account of character- 

 istics which are merely sexual. The observer should be trained to 

 discover the sexes of crania and sexual characteristics dis- 

 tinctly and clearly. When the groups are formed, the crania 



