210 Referate. 
Zucht von diesen beiden Arten, Bastardzuchten von Str. purpuratus 3 >< 
Franciscanus 2, franciscanus 5 >< purpuratus 2, purpuratus 2 >< Asterias ochracea, 
franciscanus 2 >< Asterias ochracea. 
All diese verschiedenen Kulturen erlauben auf Grund ihrer groBen 
Anzahl folgende beide Tatsachen gleichmäßig zu erkennen: I. Das Pluteus- 
skelett weist zwar eine starke Variationsbreite auf, welche aber in den 
hybriden Zuchten nicht größer ist als in den reinen. — 2. Alle Bastard- 
zuchten haben ausnahmslos den Charakter der rein mütterlichen Zucht. 
So z. B. sind die Pluteuslarven der normal besamten und der partheno- 
genetisch gezogenen Strongylocentrotus franciscanus von denen aus Asterias 3 
x Str. franciscanus 2 und Str. purpuratus 3 >< franciscanus 2 nicht zu unter- 
scheiden, und vice versa. Kammerer-Wien. 
Lutz, F. E. The variation and correlations of certain taxonomic characters 
of Gryllus. Carnegie Institution, Publ. No. 10I pp. I—63, Igog. 
This paper contains a thorough and careful analysis of the „species 
problem“ in a single concrete case. The native crickets (genus Gryd/us) of 
the eastern United States have been divided into tive so-called species. 
These five species are distinguished by the taxonomist on the basis of a 
series of specific characters. Lutz set for himself the problem of deter- 
mining what were the actual facts regarding variation in these so-called 
specific characters, when crickets were collected from a series of represen- 
tative localities over the whole eastern United States, and when these 
characters were carefully measured and the variation data thoroughly 
analyzed by exact biometrical methods. The results obtained are of much 
interest and significance to the student of evolution: The general result 
obtained was that in the genus Gry//us „species“ are matters of fluctuating 
variation; they are not formed by the addition or subtraction of definite 
unit characters. Instead it appears that under a particular set of definite 
local conditions we may get a group of individuals (species) having some 
characters quantitatively different in a definite way from the condition 
found in another group of individuals in another locality. This portion of 
his discussion Lutz very well summarizes in the following words: ,,Out of 
it all there is one thing clear, it seems to me: Either we simply name 
stages in a great continuous mass of variations and call them species, or 
there is but one species of Gry//us in the eastern United States, and the 
names we give are not the names of species at all, but simply inaccurate 
shorthand expressions for recording the approximate size, proportions, and 
color of the individuals found. In the latter case we need more names. 
It is scarcely conceivable that the species so named are—all of them, at 
least—separated by sterility barriers, so that they have any real entity. 
They are merely convenience species.‘ 
Considerable space is given to the discussion of the dimorphism of 
the wings in Gryllus. The short winged condition is held to be the newer 
condition phylogenetically, and a degeneration. The short-winged and 
long-winged groups do not intergrade; each varies about its own mean. 
Short winged forms have their organs more variable and slightly less clo- 
sely correlated than long winged forms. The short winged condition is held. 
to satisfy all the criteria of a mutation, but it has not given rise to a 
„good‘“ species. 
Lack of space forbids mention here of many of the suggestive points. 
of fact and of speculation brought out in the memoir. 
