TO SPECIES, ACCORDING TO PREVIOUS INVESTIGATORS. 135 



differences between these are to be detected), because it is only applicable 

 to fresh blood and can not be applied to blood stains, at least if they are more 

 than two weeks old. Friboes also attacks Moser's conclusion that the 

 crystals serve to distinguish between human and animal blood. He states 

 that normal human blood treated in the way described by Moser crystallizes 

 in various forms, and that the crystals from dried human blood are different 

 from any of these. Human blood obtained from the splenic vein and the 

 umbilical vessels is again different from these, so that a uniform crystal 

 shape for human blood does not exist. Thus, from fresh human blood are 

 obtained 4-sided doubly refracting prisms, also sharp-angled rods split into 

 brush-like forms at the end, and very characteristic rectangular plates 

 arranged in step-like aggregates. From the blood of a young child he 

 obtained long rectangular plates which he regards as still different. From 

 the splenic vein he found crystals showing composite aggregates of the step- 

 like arrangement of the rectangular plates. From the blood of the umbilical 

 vessels he prepared rosette aggregates of ray-like crystals, and in this 

 same blood he also noticed sheaf-like bundles of crystals and also isolated 

 irregular crystals. The blood of other animals showed still other forms, 

 which, however, are usually distinguishable from the crystals obtained 

 from normal human blood, with the exception of those from the blood of 

 the bat and goat. The distinction from human blood depends, he states, 

 upon having a sufficient supply of blood and in obtaining it before it 

 becomes dry. 



The article by Friboes is illustrated by excellent photomicrographic 

 reproductions of some of the blood crystals examined, but his descriptions 

 of the crystals are very brief and in many cases incorrect. Thus, in the 

 description of the crystals from the cat he enumerates three kinds of crys- 

 tals and illustrates them by two photomicrographs. These three types are 

 (1) long, 3-sided prismatic rods, single or in bundles; (2) 4-sided prisms, 

 rhombic ; (3) fine needles. He points out in the photomicrographs what he 

 designates the "3-sided rods," which are evidently only an edge view of 

 what he reports as " 4-sided prisms. " The fine needles are simply the same 

 crystals in capillary form. All of these belong to the long prismatic type of 

 crystal of cat reduced hemoglobin, and he appears not to have observed 

 the short prismatic type nor the parallel growth aggregates that are usual 

 in the preparation from cat's blood. His "fine needles" are generally the 

 first crystals to appear, and his other two types, which he regards as distinct 

 (one trigonal, the other rhombic), are but two views of the same crystal. 

 The foregoing is simply an example of how an expert microscopist who is 

 not a crystallographer may be misled by different appearances that he is 

 unable to reconcile. 



The objections recorded in opposition to the conclusion of Kunde and 

 others that the blood crystals from different species are not identical and 

 that they are characteristic of the species may be summarized briefly as fol- 

 lows : The form of the crystal of any species may be entirely accidental and 

 dependent upon exterior conditions, and hence can not be characteristic 

 of the species. In the same species different forms of crystals may be seen 



