USTILAGO. 



[ 667 ] 



UTERUS. 



expense of the tissue and juice of the infested 

 organ, and is finally converted into a pulve- 

 rulent mass of simple spores, mostly of deep 

 colour, and with a smooth, spiny or reticu- 

 lated surface. 



The species growing upon leaves and 

 stems occur on grasses, e. g. U. longissima 

 (Uredo longissima, Sow.), U. hypodytes (Ur. 

 hypodytes) and U. grandis (or typhoides)-, 

 they form linear patches, ultimately con- 

 taining smooth black spores. 



The greater number, however, occur in 

 the parts of flowers, especially of grasses; 

 as Ust. Carbo (Uredo segetum, Pers.), form- 

 ing the blight called smut of com, com- 

 monly infesting wheat, oats (fig. 791), barley 

 (fig. ^92) and other grasses, filling the ears 

 with a black powder of smooth spores, about 

 1 -5000" in diameter in corn, sometimes about 



Fig. 793. 



/ 



Portion of a spike of Maize infested with Ustilago 

 Maidis. Some of the lower grains perfect and mature ; 

 above these, female flowers with abortive ovaries. The 

 projecting bodies are grains which have become deformed 

 by the Ustilago developed within them. 



twice as large in the varieties attacking 

 species of Bromus. The smut of maize ( U. 

 Maidis, fig. 793) has minutely echinate 

 spores, 1-2500" in diameter. 



Sedges are infested by Ust. urceolarum 

 with dark brown, and Ust. olivacea with 

 olive-coloured spores ( Uredines, Brit. Flor.). 

 Ust. antherarum, growing in the anthers of 

 Caryophyllaceae, has violet-coloured spores. 

 Many other species are described by Tulasne, 

 several of which have occurred in Britain. 



BIBL. Tulasne, Ann. des Sc. nat. ser. 3. 

 vii. p. 73; ser. 4. ii. p. 157; Berk. Brit. 

 Flor. art. Uredo ; Ann. Nat. Hist. ser. 2. v. 

 p. 463. 



UTERUS. The substance of the uterus 

 consists of longitudinal, transverse, and 

 oblique, unstriated muscular fibres, inter- 

 woven with imperfectly developed areolar 

 tissue, resembling that in the stroma of the 

 ovary. 



Three layers of the muscular fibres are 

 described, but they are intimately connected. 

 Those in the cervix are principally trans- 

 verse or circular ; and imme- 

 diately beneath the mucous 

 membrane at the mouth of 

 the uterus, the transverse 

 fibres form a sphincter. 



The muscular fibres are 

 from 1-600 to MOO" in 

 length, fusiform, with elon- 

 gate oval nuclei, and very 

 difficultly separable on ac- 

 count of the large amount of 

 areolar tissue intermingled 

 with them. 



The epithelium is simple 

 and ciliated. The mucous 

 membrane of the body has 

 no papillae, but here and there 

 some folds, and contains nu- 

 merous tubular or uterine 

 glands resembling the Lie- 

 berkuhn's glands of the in- 

 testines, their csecal ends 

 being simple, bifurcate, or 



spiral, and Consisting of a fibres, three weeks 



basement-membrane with cy- after parturition, 

 linder-epithelmm. Sr^jOT, 



In the cervix are situated y, globules of fat. 

 glandular depressions of the Magnified 

 mucous membrane, which ^**^ e *T 

 secrete a transparent tenacious mucus ; some 

 of these are closed, and form the ovules of 

 Naboth. 



The lower third or half of the canal of the 

 cervix contains papillae covered with ciliated 

 epithelium. 



During pregnancy, the uterine elements, 

 especially the muscular fibres, as also the 

 vessels, and probably the nerves, become 



Uterine muscular 



