1915] CURRENT LITERATURE 421 
Germination.—MULLER® has done a very important piece of work on the 
breaking of seed and fruit coats in germination. The work deals with four 
general topics: (1) source of energy for breaking the coats; (2) structural 
3 
against the coats by the growing contents; and (4) pressure required for 
bursting the coats in germination. 
1. The author finds four different types of seeds and fruits as to the source 
of the pressure for bursting the coats: (a) swelling of the seed or fruit contents 
resulting from water absorption (swelling endosperm of Ipomaea and others, 
swelling embryo of Chenopodina maritima); (b) growth of endosperm (Pinus 
Pinea, Ricinus communis, and several others); (c) growth of cotyledons 
(Prunus persica and several other species of Prunus, Juglans regia, J. nigra, 
J. cinerea, and Corylus avellana); (d) growth of primary root or hypocotyl. 
In type (d) the author recognizes five different groups: (1) radicle borne 
between the subtending ends of the cotyledons and exerting its pressure upon 
the coat through these; (2) embryo located centrally in the endosperm and 
exerting its pressure upon the coat through this tissue (Rumex species, Ruta 
graveolens, Nigella damascena, Viola tricolor, etc.); (3) no nutrient tissue, 
embryo directly against the coat, hypocotyl in wedge-shaped cavity (Helian- 
thus annuus, Cucurbita Pepo, etc.); (4) hypocotyl peripherally placed and 
in a wedge-shaped — formed by integuments or by integuments and 
ndospe or cotyledons (Eroum lens, Phaseolus multiflorus, Saponaria 
vaccaria, Potomogeton ue etc.); (5) root or root-bearing portion of 
Gityledon generally cylindrical, pushing out through hole stopped by 
plug, lid, or valves (mostly monocots, as Marantaceae, Musaceae, Cannaceae, 
Phoenicaceae, etc.). 
2. Under structural features of fruit or seed coats related to freeing of the 
embryo, the author discusses five classes: (a) free openings through which 
embryo grows without resistance (Coix lacrymae); (b) a special hole for exit 
of the embryo, the hole being stopped by a plug, cap, or valves (Canna, Tra- 
descantia, Commelina, Sparganium, etc.); (c) a preformed dehiscent line 
(Prunus, Pinus, Juglans, Amygdalus, etc.); (d) zones of slight resistance at 
which coats break (Polygonaceae, some Lepidocaryeae); (e) no special mechan- 
ism (Trigonella foenum graecum, Ligustrum vulgare, Capsicum annuum, Allium 
species). 
3. The pressure exerted against the coats by growing contents were 
measured for three forms. The growing cotyledon of Corylus avellana develops 
pe 
munis and Pinus Pinea develop a maximal average pressure of 4539.07 gm. 
© MULLER, GOTTFRIED, Beitrige zur Keimungsphysiologieuntersuchungen iiber 
mf sa oes oe Samen- und Fruchthullen bei der Keimung. Jahrb. Wiss. Bot. 
1529-644. I 
