833 



MILDEW. 



MILK. 



831 



in the orchards of Herefordshire. It appears at first like bright 

 yellow spots upon the upper surface of the leaves ; by degrees a liquid 

 matter is exuded from them ; at the same time small conical processes 

 appear in clusters from the under side of the leaf ; these processes 

 enlarge, become fibrous, open at the sides by numerous slits, and 

 thence discharge their spores. This fungus often produces the most 

 destructive consequences, appearing upon the leaves, stems, and fruits, 

 and generally destroying the tree. Another species, JE. laceratum, 

 sometimes spreads over hawthorn hedges ; and the common orange- 

 red mildew of the Berberry is jE. Serberidis. 



5. Sclerotium, a hard kernel-like fungus, is a less common but some- 

 times very troublesome visitor. S. compact-urn occasionally establishes 

 itself in the rind of fruits, rendering them uneatable ; S. Cyparissice 

 and others attack the leaves of various plants, particularly of the 

 pear-tree. 



In all these cases it is usually found that the most vigorous indi- 

 viduals are the first affected by the mildew, especially in the case of 

 Uredo and Puccinia ; and it is probable that the spores from which 

 these plants are propagated are drawn into the circulation from the 

 soil, along with the fluid matter on which plants feed ; that they are 

 carried along into the stem, and begin to grow as soon as they find 

 themselves in a suitable situation, disturbing and disorganising the 

 tissue by the production of their spawn, and taking to themselves that 

 nutriment which would otherwise have been applied to the general 

 maintenance of the plant attacked. Mr. Bauer found that he could 

 always < aise wheat to produce the Uredo foetida by rubbing its grains 

 with the spores of that fungus previous to their being sown ; and Mr. 

 Knight ascertained that by sowing pear-seeds in soil infested with 

 the sEcidium, the very youngest leaves of the seedling plants were 

 attacked. 



Of superficial Fungi the following are the most remarkable : 



1. Cylindrotporium concentrlcum, a pulverulent species, which 

 appears in dots arranged in a circular manner upon the leaves of the 



2. Acrotporittm monilioidet. A frequent cause of the whiteness of 

 leaves and stems in roses, &c. It consists of vast multitudes of fila- 

 ments jointed like a necklace. 



3. Botrytis difftaa and species of the genus Aspergillus, whose fila- 

 ments bear tufts or branches, covered with spores. These form the 

 white mealy appearance of the leaves of onions and similar soft-leaved 

 plants. 



4. Erytiphe communif, which forms the mildew of peas. It con- 

 gists of white cobweb-like spawn, radiating from a solid gray spherical 

 centre, filled with the spores of the species. Peach mildew is often 

 caused by another of this genus, the E. pannosa. 



The attacks of superficial Fungi are generally brought on by the 

 debility of the species attacked ; and it is probable that unhealthy 

 individuals only are suited to the growth of these parasites. This is 

 like what occurs among animals, which, when healthy, are scarcely 

 attacked by parasitical vermin, but as soon as they become sickly are 

 overrun by them. Heavy rains occurring suddenly after long drought 

 are mentioned as a cause of this kind of mildew ; and it may be sup- 

 posed that the plants are debilitated by the dry weather, at which 

 time the Punyi seize upon them, and that as -soon as rain falls they 

 grow with rapidity and quickly overrun the plants. It is said that 

 deep-coloured roses and peaches are more liable to mildew than others; 

 this may be referred to constitutional debility, for their colour is con- 

 nected with a want of power to decompose carbonic acid, which is one 

 of the most indispensable of vital functions in the vegetable kingdom. 

 Transplanted onions, which are less vigorous than untransplanted 

 ones, are the most subject to mildew. 



These causes of mildew being rightly understood, the methods of 

 preventing the evil are sufficiently obvious. To cure intestinal mildew 

 the soil should be neither too rich nor too freely watered, and every 

 precaution should be taken to prevent the spores of the mildew-plants 

 from being communicated to the soil. Mr. Knight stopped the attacks 

 of jEcidium cancellatum by taking up his mildewed pear-trees, washing 

 their roots clean, pruning them closely, and removing them to a new 

 situation ; thoso removed became healthy, those left in the soil event- 



ually perished. It would also appear that in some cases plants may 

 be rendered incapable of taking the mildew. Mr. Bauer says that if 

 corn attacked by pepper-brand is soaked in lime-water for at least 

 twelve hours, and then well dried in the air before sowing, not only 

 are all the Fungi adhering to it destroyed, but the plants themselves 

 are incapable of nourishing the fungus ; at least he found that pre- 

 pared grains could not be inoculated, although unprepared grains 

 could be. With regard to destroying superficial mildew, a restoration 

 of vigour or its preservation seems to offer the best chances of success. 

 Mr. Knight prevented his peas from mildewing by watering them 

 abundantly and constantly ; in Scotland, where the climate is more 

 equable than in England, and the night dews more abundant, pea- 

 mildew is unknown. The writer of this has seen a crop of onions 

 perishing under the attacks of Botrytis diffusa gradually restored to 

 health by a constant supply of water. As to the schemes of stopping 

 superficial mildew by the application of sulphur, quick-lime, fresh 

 wood-ashes, and similar substances, all of which have been recom- 

 mended, it does not appear that any advantage follows their employ- 

 ment. When trees are attacked by superficial parasites the best plan 

 of removing the evil is by cutting off all the mildewed branches and 

 destroying them, together with shreds, nails, or whatever else may 

 have been made use of in training the plants. Mr. Hayward recom- 

 mends in addition that peach-trees, which are very liable to mildew, 

 should be subsequently washed with a fluid consisting of 4 gallons of 

 rain-water, 21bs. of soft soap, lib. of flower of sulphur, lib. of roll 

 tobacco, 1 quart of fresh-slaked lime, and 1 pint of spirits of turpen- 

 tine, the whole boiled together for half an hour. 



For a further account of the Fungi which produce diseases of plants 

 see FUNGI. 



MILIOBATIS. [SQUALID*:.] 



MFLIOLA. [FORAMINIFERA.] 



MI'LIUM, a genus of Grasses belonging to the tribe Agrostidea. It 

 has membranous glumes, nearly equal, unarmed ; the palete 2, nearly 

 equal, unarmed, about as long as the glumes, and hardening on the 

 the fruit ; the spikelets convex on the back, or slightly dorsally com-, 

 pressed. There is but one British species of this genus, M. effusum. 

 It has a diffuse panicle, with acute palese, a smooth stem, and 

 linear-lanceolate leaves. It has a. stem 3 or 4 feet in height, and 

 is found in damp shady woods. (Babiugton, Manual of British 

 Botany.} 



MILK is an opaque fluid, secreted by the mammary glands of the 

 females of the animals belonging to the class Mammalia, and adapted 

 to the nourishment of their young offspring. It is of a specific gravity 

 somewhat greater than that of distilled water, and possesses a peculiar 

 odour, which is due to several acids. It consists, in addition to the 

 watery portion, serum, &c., of globular particles, which are not more 

 than half the size of the globules of human blood, having a diameter 

 of about 1-1 0,000th of an inch. They are composed of a fatty matter 

 (butter) and a coagulable substance, which in many points resembles 

 albumen, termed ' caseum,' or ' caseine.' 



The globules are specifically lighter than the fluid in which they are 

 suspended, and easily ascend to the top when the milk is allowed to 

 stand. This constitutes the cream, and consists of the butter, with 

 some caseine and a portion of serum. By agitation, such as is effected 

 by the various modes of churning, the fatty globules unite into a 

 mass (butter), leaving the buttermilk, which consists of caseine and 

 serum. 



Milk from which the supernatant fluid, or cream, has been removed is 

 termed ' skim-milk,' and still retains a considerable q uantity of coagulable 

 or caseous matter, which may be separated from the serum, or whey, by 

 means of a rennet or any acid. This coagulated portion constitutes 

 the curd, and is the basis of cheese. If a rennet be used, and all the 

 portion coagulated by its means be separated, the addition of vinegar 

 causes some of what remains to coagulate ; and this has been termed 

 ' zieger' by Schubler, but it is not certain that it differs from caseiue. 

 What remains after both these coagulated principles have been removed 

 is the whey, which contains sugar-of-milk, some azotised substance 

 (perhaps osmazome), lactic acid, and various salts. 



The different constituents of milk, and the differences in the rela- 

 tive proportions of them in some of the common domestic animals 

 will be best seen in the following tables : 







[Fatty matter, solid at ordinary temperatures Stear'me. 



fBy saponification, yielding Butyric, Caproic, Capric, Margaric, and Oleic Acids, and) 



[ Liquid Fatty] Glycerine I Ji ""J r '" e - 



Matter .1 



saponification, yielding no Butyric, Caproic, nor Capric Acids 



Milk 



I Skim-Milk . 



(_ Serum or Whey 



Oleine. 



............. Caseine or Curd. 



st, but by Acetic Acid .......... Zieger. 



f Azotized Matter Osmazame (1) 



Lactic Acid. 



Sugar Sugar of Milk. 



Salts 



f 



I Soluble in Alcohol 



. goluble 





in Waterj 



not in Alcohol , 



Lactates of Potash, Soda, Ammonia, Lime, and Mag. 



nesia. 



Chlorides of Potassium and Sodium. 

 Sulphate of Potash. 

 Phosphate of Potash and Soda. 



HAT. HI8T. DIV. VOL. III. 



(^Insoluble in Water Phosphates of Lime, Magnesia, and Iron. 



3 H 



