Toit] CURRENT LITERATURE 149 
sharp. Since the sexual cells are from the peripheral white portion, the seed- 
lings give pure white forms. White branches give only white forms vegeta- 
tively, and green branches only green forms. If a pure white and a pure green 
form are hybridized sexually, there result, besides pure white and pure green 
offspring, green-white mosaics. If in the latter the growing point is situated 
on the line between the white and green portions, there results a chimera, such 
as WINKLER obtained so frequently in Solanum. Since in a cross-section of 
a stem the two components appear as sectors, BAUR has given to such forms the 
name sectorial chimeras. For the condition that Baur finds in an ordinary 
Pelargonium with white-margined leaves, he gives the name periclinal chimeras, 
one of the components investing the other; in Pelargonium the growing point 
is periclinally divided into white and green cells, the former outermost, so that 
the entire plant is composed of a body of green geranium invested by a mantle, 
two or three cells deep, of white geranium. In referring to WINKLER’s work, 
BAurR suggested that the so-called graft hybrids of Solanum probably are peri- 
clinal chimeras. In another paper? he discusses STRASBURGER’S theories 
concerning hyperchimeras, noting that such an irregular mixture of the ele- 
ments of the two component forms can hardly give rise to such definite struc- 
tures as the so-called graft hybrids. Very recently Baur has published a 
ally. He has discovered also that Crataegomespilus is a periclinal chimera, 
the form known as C. Asnieresii being composed of a Crataegus body with a 
Mespilus epidermis; while the form known as C. Dardari has a Mespilus 
periphery of two cell layers. Laburnum Adami, which has been a riddle for 
nearly a century, proves to be a periclinal chimera, with an epidermis of 
Cytisus purpureus and a body of Laburnum vulgare; seedlings are always the 
latter, because the hypodermal layer, which gives rise to the sex cells, 
is of that species. When the peripheral species is composed of two or more 
layers, the seedlings are of that species, as in Pelargonium. One of the most 
interesting features of a situation that is throughout of absorbing interest is 
that Baur’s remarkable discovery was almost made by MACFARLANE™ fifteen 
years ago, as BAuR himself points out. MACFARLANE made a careful anatom- 
ical study of Laburnum Adami in comparison with Cytisus purpureus and 
Laburnum vulgare, and an examination of his figures shows clearly that 
e 
very striking resemblance which the epidermis of the hybrid portion has 
to that of C. purpureus . . . . would seem at first sight to prove that 
UR, Erwin, shes greg! beagle 2 site und Hyperchimiren. Ber. 
erties “Bot Gesell. 2'7: 603-605. 
re , Propfbastarde. Biol ‘Gendiatht 30:407-514. figs. 7. IQI0. 
** MAcFARLANE, J. M., A comparison of the minute structure of plant — 
with that of their parents, and its bearing on biological problems, Trans. Roy. Soc 
Edinburgh 37: 203-286. 1895. 
